Epicurus Against Aristotle On Atomism

This document has been prepared by ClaudeAI at the direction of Cassius Amicus. It draws on Epicurus’s surviving texts (Bailey translations), Aristotle’s Physics and De Generatione et Corruptione (Ross and Williams translations), and the modern scholarship of Furley, Konstan, Vlastos, Sedley, and Long and Sedley on the relationship between Aristotelian philosophy of mathematics and Epicurean atomic theory. The first edition of this work was produced on April 27, 2026. Comments are encouraged and revisions are ongoing.

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Introduction: A Debt Epicurus Would Not Deny

Ancient philosophical schools were not in the habit of acknowledging their debts to rivals, and Epicurus was less inclined than most to acknowledge debts to anyone. His attitude toward earlier philosophers was famously dismissive — including toward Democritus, the founder of the atomic theory he inherited and transformed. Yet the evidence of Epicurus’s own texts — most directly the Letter to Herodotus — makes clear that the shape of his atomic theory was determined in significant part by his engagement with a critic neither he nor anyone else could simply dismiss: Aristotle.

The specific doctrine at issue is the Epicurean theory of minimum parts (elachista, sometimes rendered minima from the Latin of Lucretius). This technically sophisticated doctrine cannot be understood in isolation. It was not an independent discovery. It was, as David Furley’s foundational analysis in Two Studies in the Greek Atomists established, and as David Konstan’s subsequent work in “Problems in Epicurean Physics” extended and refined, Epicurus’s carefully considered response to a set of philosophical objections that Aristotle had pressed against the original Democritean form of atomism with sufficient force to make that original form philosophically untenable.

This article reconstructs Aristotle’s objections in their main lines, identifies the specific passages in which they are developed, and then traces in detail how Epicurus modified atomic theory to answer each one — showing both where he accepted Aristotle’s logic and where he constructed a genuinely original philosophical alternative to the conclusions Aristotle drew from it.

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Part One: Democritean Atomism and Its Vulnerabilities

What Democritus Actually Claimed

To understand what Aristotle was objecting to, it is necessary first to be clear about what Democritus had actually proposed. The original Democritean atomic theory, as best we can reconstruct it from the surviving testimonies, held that the fundamental constituents of reality are atoms and void. Atoms are absolutely solid, containing no void in their interior; they are therefore physically indivisible. They differ from one another in shape, size, and arrangement, and all perceptible qualities of composite objects are produced by the configurations and interactions of these atoms in the void.

On the question of the atoms’ size and structure, Democritus appears to have held that atoms were themselves partless — that is, that they were genuine indivisibles in the sense that they had no internal structural parts at all. This was the philosophical position that gave atomism its name and its claim to resolve the Eleatic paradoxes: if there are genuine physical indivisibles, then the regress of division cannot proceed without limit, and Zeno’s paradoxes about infinite division lose their force. The atom was the floor, below which matter could not be further divided.

It was also, as Aristotle saw clearly, a position that generated its own serious philosophical problems.

The Confusion Aristotle Identified

A crucial ambiguity in Democritean atomism, which Aristotle’s analysis brought to the surface, concerned the relationship between two things that Democritus appears to have identified: being physically indivisible and being geometrically partless. For Democritus, the atom seemed to be both at once — it was a unit of matter that could not be divided, and it was a unit of matter that had no internal geometric structure, no parts at all, not even in the abstract sense of having a left side and a right side or an interior and an exterior.

Aristotle recognized that this conflation was philosophically dangerous. A body that is physically indivisible need not be geometrically partless. A body can have geometric structure — can have surfaces, edges, corners, an interior and an exterior — without this geometric structure corresponding to physically separable sub-units. The distinction between physical divisibility and geometric structure is, in retrospect, obvious. Aristotle’s achievement was to press it systematically against the Democritean framework and show that the conflation of the two had produced a theory riddled with internal contradictions.

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Part Two: Aristotle’s Arguments — The Texts and Their Force

Aristotle’s most sustained and technically developed critique of atomic indivisibles appears in two main locations: Book VI (called Zeta in the older notation) of the Physics, and Book I of De Generatione et Corruptione. A full reconstruction of his argument requires both.

The Continuity Argument: Physics Book VI, Opening Passages

The opening paragraphs of Physics Book VI constitute one of the most concentrated pieces of analytical argumentation in Aristotle’s entire corpus. Aristotle begins by defining three spatial relationships with precision: things are continuous when their extremities are one and the same; they touch when their extremities are together (but remain two, not one); they are consecutive when nothing of the same kind lies between them. He then argues, on the basis of these definitions, that no continuous magnitude can be composed of partless entities.

The argument runs as follows. If a line were composed of points — indivisible, partless entities — then those points would have to stand in one of the three defined relationships to each other: they would be continuous with each other, or touching each other, or merely consecutive. But:

First, they cannot be continuous with each other, because continuity requires that the extremities of two things be one and the same, and a partless entity has no extremity distinct from the entity itself — there is no boundary that could be identified with the boundary of a neighboring entity.

Second, they cannot touch each other in the proper sense, because touching requires that two distinct extremities be together, and again, a partless entity has no distinct extremity. As Aristotle puts it: “there is no boundary at all of the partless thing; for the boundary is a different thing from that of which it is the boundary.” A point does not have a boundary; it simply is a location.

Third, they cannot be merely consecutive with nothing between them, because between any two points there is always a line, and a line is not a point. Points cannot be arranged consecutively in the way that, say, whole numbers can be arranged consecutively (with no whole number between 3 and 4), because the domain between any two points is not a point-free zone but a continuous segment.

Aristotle’s conclusion: “Clearly, then, every continuity is divisible into forever divisibles; for if it were divisible into indivisibles, we should have an indivisible in contact with an indivisible, since the extremities of continuous things are one, and that which is continuous is divided into things whose extremities are in contact.” (Physics VI.1, 231b15-18)

The force of this argument against Democritus is direct. If Democritean atoms are truly partless indivisibles in the geometric sense, they cannot touch each other, because partless things have no extremities to be “together.” They cannot be continuous with each other for the same reason. They can be consecutive — separated by a void — but then the composite bodies formed from them would be nothing more than a collection of isolated particles with no genuine physical continuity between them. The solid, continuous surfaces of ordinary composite objects would be impossible to account for.

The Motion Argument: Physics Book VI on Indivisible Magnitudes in Motion

Aristotle further develops his analysis by considering what must follow if indivisible magnitudes actually exist. His argument in the middle sections of Physics Book VI establishes that if there are indivisible units of spatial extension, then there must correspondingly be indivisible units of time and of motion — and that this produces a consequence that is either paradoxical or empirically untenable.

The argument proceeds through the observation that if a body traverses an indivisible spatial unit, it must do so in some definite amount of time. If that amount of time is itself divisible, then at some intermediate moment the body would be located at an intermediate point within the spatial unit — but if the spatial unit is indivisible, there is no intermediate point to be located at. Therefore the time in which a body traverses an indivisible spatial unit must itself be indivisible. Similarly for motion: the “moving” across an indivisible spatial unit must itself be an indivisible unit of motion, not a process that has stages.

This has a further consequence, which Aristotle presses: if all motion is composed of indivisible units of motion, each of which involves traversing one indivisible spatial unit in one indivisible temporal unit, then there can be no real differences in the speeds of objects. One object traversing two spatial units in two temporal units and another traversing one spatial unit in one temporal unit are moving at exactly the same speed, in the only sense of “speed” that the framework allows. Apparent differences in speed at the perceptible level must be accounted for in some other way. As Furley summarizes Aristotle’s conclusion: Epicurus was forced to accept “that faster and slower motion entails the divisibility of time and distance” and therefore had to develop the theory that “there are no real differences in the speeds of visible moving bodies” at the atomic level — that all atoms move at the same speed, with apparent differences at the perceptible level accounted for by the varying density and configuration of compound bodies rather than by genuine differences in atomic velocity.

The Contact Problem: De Generatione et Corruptione Book I

In De Generatione et Corruptione Book I, Chapter 8, Aristotle develops a related but distinct objection specifically targeting the physical interaction between atoms. His concern here is with the question of what it means for two partless entities to be “in contact.” If Democritean atoms are genuinely partless — having no geometric parts, no interior distinct from exterior, no surfaces that are genuinely distinct parts of the atom — then when two atoms come into contact, the contact must be “whole to whole.” One whole partless atom touches another whole partless atom.

But “whole to whole” contact, Aristotle argues, is indistinguishable from overlap or merging. If atom A and atom B are each partless wholes, and A touches B “whole to whole,” there is no geometrical basis for saying that A ends and B begins. The two atoms, in physical contact, become indistinguishable from a single merged entity. The atomic impenetrability that Democritus required — the principle that no two atoms can occupy the same place — has no physical basis if atoms are partless, because there is nothing in the concept of a partless entity that establishes a definite boundary between it and another partless entity with which it is in contact.

This is the argument that Konstan, in his “Problems in Epicurean Physics,” correctly identifies as the most fundamental challenge to Democritean atomism. As Konstan puts it, the problem can be stated as a dilemma: “between the two atoms there is no void. How then can they be separated, if indeed bodies can only be divided by cutting along the space between them, solidity being nothing but the absence of this space?” Two adjacent atoms with no void between them and no geometric internal structure are, by the terms of Democritean physics, indistinguishable from a single larger atom. The theory cannot account for the fact that atoms in contact remain distinct particles that subsequently separate.

The Zeno Connection: The Arrow and the Moving Rows

Aristotle also invokes the Zenonian paradoxes in a way that bears directly on atomism. The paradox of the arrow — that an arrow in flight cannot change its position in a single instant, and that therefore at any instant it is at rest, and that if it is at rest at every instant it cannot be in motion at all — was one that Democritean atomism was intended to resolve. If there are genuinely indivisible moments of time, then motion can be understood as a series of discrete jumps from position to position, and Zeno’s paradox loses its force.

But Aristotle shows that indivisible temporal moments generate their own version of the difficulty. If at any given moment an atom simply occupies a position — if there is no such thing as “being in the process of moving” within a single indivisible moment — then what distinguishes a moving atom at any given moment from a stationary atom? Konstan frames the problem precisely: “what is it that distinguishes a moving atom at a given moment from a stationary one? If nothing, then why does the moving atom continue to move (or the stationary atom remain at rest)?” The description of an atom at a single moment, if that moment is indivisible, gives no information about whether the atom is moving or at rest. The concept of motion seems to have evaporated entirely.

Aristotle also developed the so-called “Moving Rows” paradox (Physics VI.9, 240a4-240b7), which targets the specific case of indivisible bodies moving past each other in opposite directions. If three rows of indivisible bodies move past each other, it is possible to construct scenarios in which an indivisible body passes another indivisible body in half an indivisible unit of time — which the framework should prohibit, since the time unit is supposed to be indivisible. The paradox shows that indivisible magnitudes of space and time, taken together, generate contradictions in the description of relative motion.

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Part Three: Epicurus’s Response — Accepting What Had to Be Accepted, Modifying What Could Be Modified

The sophistication of Epicurus’s response to Aristotle lies in its structure: he did not simply reject Aristotle’s arguments. He accepted the ones he could not refute, drew the conclusions that followed from them, and then constructed a modified atomic theory that incorporated those conclusions while preserving the materialist framework he had inherited from Democritus. The result is a theory significantly different from Democritus’s in its internal architecture, even though it retains the same foundational ontology of atoms and void.

First Move: Separating Physical Indivisibility from Geometric Partlessness

The most fundamental modification Epicurus made was to sever the identification between physical indivisibility and geometric partlessness that Democritus had left implicit and that Aristotle’s arguments had shown to be untenable.

For Epicurus, the atom is physically indivisible — it cannot actually be split — but it is not geometrically partless. The atom has an interior and an exterior, surfaces and edges and corners. It has what Epicurus called minimum parts (elachista) — genuine structural components distinguishable in reason, even though they cannot exist as independent physical entities and cannot be separated from the atom to which they belong.

This is the crucial innovation, and it requires careful statement. Konstan, working from the evidence of Epicurus’s own Letter to Herodotus and Lucretius’s De Rerum Natura, emphasizes the importance of distinguishing the minimum part from the atom itself: “Epicurus decisively separated the two arguments when he lifted from the atom its status as minimum or partless entity, attributing this feature to his (presumably) novel concept of smallest bits (elachista, minima) which themselves cannot have an independent existence (hence cannot be atoms).” The atom became, in Epicurus’s reformulation, a body of whatever size (though in practice imperceptibly small) composed of minimum parts, and defined by the total absence of any internal void — not by the absence of geometric structure.

Solidity and indivisibility, which Democritus had grounded in the same property (being partless), are now grounded in different properties in the Epicurean system. Solidity — the impossibility of matter dissolving into nothing — is grounded in the absence of internal void in the atom: matter cannot be divided where there is no void to divide along. Indivisibility as the minimum unit of spatial extension is grounded in the properties of the minimum part itself. These are two distinct lines of argument, kept distinct by Epicurus for reasons that are not merely pedantic but structurally required by his response to Aristotle.

Second Move: The Minimum Part as Unit of Extension

What exactly is a minimum part, and how does its introduction address Aristotle’s arguments? This is where the greatest scholarly debate has concentrated, and where the work of Furley, Vlastos, and Konstan is most valuable.

Vlastos, in his “Minimal Parts in Epicurean Atomism,” establishes that the minimum part is not a geometric point but a genuine unit of spatial extension — the smallest possible increment of size. This is what Epicurus means in the Letter to Herodotus sections 56-58 when he describes the minimum as a unit that “admits of measurement, larger by more of them, smaller by fewer” — the minimum part is the unit in terms of which sizes are measured, analogous to the unit in arithmetic. Just as the number 5 is five counting units and the number 3 is three counting units, a large atom is more minimum parts and a small atom is fewer minimum parts.

The critical property of the minimum part, and the property that addresses Aristotle’s continuity argument, is that it has genuine extension in all three dimensions — it has a definite size, however small — but it has no further internal geometric structure. Furley’s analysis shows that Aristotle himself, in his discussion of continuity, implicitly requires something like this distinction. Aristotle’s argument that a line cannot be composed of points depends on the fact that points are dimensionless — they have no boundary distinct from themselves. If the “indivisible” units from which a line is composed were not dimensionless but instead had some definite, if minimal, extension, Aristotle’s argument would not go through in the same form.

Epicurus’s minimum parts are extended in this way. They are not points. They have a left side and a right side, a front and a back, that can be distinguished in thought — Epicurus acknowledges this explicitly in sections 58-59 of the Letter to Herodotus — but they do not exist as divided things, and they are not composed of further sub-units. The conceptual distinguishability of their sides does not entail physical separability. This is the key move that addresses Aristotle’s first objection: Epicurus is not trying to compose a continuous line out of dimensionless points but out of minimally extended units. The surface of an atom is not a geometric surface of zero thickness but a physically real layer of minimum parts with definite, if minimal, extension.

Furley quotes Epicurus on this directly from Letter to Herodotus 58: “We examine these beginning from the first and not in the same spot, nor touching parts to parts, but in their own nature as things that measure sizes, more of them measuring a greater thing and fewer of them a lesser.” This passage shows Epicurus engaging directly with Aristotle’s language of “touching” and “contact” and proposing that minimum parts stand in a relationship to each other that is neither the “whole-to-whole” contact of Democritean partless entities nor the “part-to-part” contact that Aristotle’s framework requires — but something else: they are units of measure whose arrangement constitutes magnitude without requiring that each unit be geometrically bounded in the way Aristotle’s framework assumes.

Third Move: Addressing the Contact Problem

The contact problem — how two atoms in physical contact retain distinct identities — is addressed by the minimum part doctrine in the way Konstan’s analysis makes most clear. Because atoms are composed of minimum parts that have genuine extension in all three dimensions, atomic surfaces are not geometric abstractions but physically real outer layers of minimum parts. When atom A and atom B are in contact, the contact is between the outermost minimum parts of each atom, not between the whole of one dimensionless entity and the whole of another.

This means the identity of each atom at the point of contact is established by the physical reality of its surface minimum parts, which are genuine parts of that atom and of no other. The boundary of atom A is determined by the minimum parts that belong to atom A; the boundary of atom B is determined by the minimum parts that belong to atom B. The void that separates atoms is not required to extend between every pair of surface atoms; the physical distinctness of the atomic surfaces, grounded in the minimum part structure, establishes the boundaries without requiring interstitial void at every point of contact.

Konstan’s formulation of this conclusion deserves direct quotation: “With the Aristotelian concept of boundary, made physical by endowing it with actual if minimal extension in all dimensions, Epicurus drew the line that divided contiguous substance.” The phrase “made physical” is the critical one. Aristotle himself used the concept of boundary in his analysis of continuity, but for Aristotle the boundary of a physical body is a geometric abstraction — a surface of zero thickness, a mathematical concept rather than a physical entity. Epicurus takes this concept and gives it physical reality by identifying it with the minimum parts that constitute the outer layer of the atom. The boundary becomes a physical thing, not a mathematical abstraction, and in doing so it solves the contact problem that Aristotle had identified.

Konstan further notes, drawing on Diogenes Laertius’s Life of Epicurus (10.28), that Epicurus apparently wrote two specific works on questions directly related to these contact and boundary issues: On the Corner in the Atom (Peri tês en tôi atomôi gônias) and On Contact (Peri haphis). The very existence of these treatises confirms that Epicurus devoted sustained and detailed attention to precisely the problem that Aristotle’s analysis had posed, and did not regard it as a minor technical footnote but as a philosophically central question about the foundations of atomic theory.

Fourth Move: Accepting Quantum Motion

Epicurus’s response to Aristotle’s arguments about indivisible magnitudes in motion is, in one respect, the most striking of all his responses: he simply accepted the consequence that Aristotle had drawn. If there are indivisible units of spatial extension, then motion must be discontinuous — an atom traverses one unit of space in one unit of time, and there are no intermediate states within that traversal. At any given moment of time, an atom is not in the process of moving; it either is at one position or has moved to the next. The correct description of an atom’s behavior at any moment is not “it is moving” but “it has moved.”

Furley documents this acceptance carefully, showing how Epicurus built Aristotle’s conclusions about the relationship between spatial and temporal indivisibles into the structure of his own physics. The principle of uniform atomic velocity — that all atoms move at the same speed — follows directly: if each atom traverses exactly one spatial unit in each temporal unit, and there are no fractions of either, then no atom can move faster or slower than any other at the atomic level. Apparent differences in the speeds of perceptible objects are produced by the interference of collisions in compound bodies, which introduces horizontal components to atomic motion that reduce the net vertical (downward) displacement per unit of time.

This was a genuinely bold philosophical move. Rather than arguing against Aristotle’s conclusions about what follows from indivisible magnitudes in motion, Epicurus incorporated those conclusions into his own physics. The quantum, discontinuous character of atomic motion that modern physics would rediscover two and a half millennia later is not an accidental feature of Epicurean atomism; it is a deliberate consequence of taking Aristotle’s analysis of indivisible magnitudes seriously.

The remaining problem — what distinguishes a moving atom at a given moment from a stationary one, if at that moment it is simply occupying a position without “being in motion” — Epicurus resolved by the postulate that all atoms are always in motion. There are no stationary atoms. An atom “at rest” at a given moment is a conceptual fiction; the physical reality is that atoms always have moved and will move, and the direction and continuation of an atom’s motion is determined by its history of interactions. The atom’s “motion” is not a property of a single moment but of a sequence of moments, and the fact that no single moment contains the property “moving” does not prevent the sequence from constituting genuine motion. As Konstan puts it: “It is essential to take into account the previous history of an atom in describing it at any given moment, because only in this way can we know whether and how it is moving with respect to other bodies.”

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Part Four: What Epicurus Did Not Accept — The Limits of Aristotle’s Authority

Epicurus’s response to Aristotle was not simple capitulation. There were specific elements of Aristotle’s analysis that he contested rather than accepted, and identifying these is as important as identifying where he conceded.

Rejecting Infinite Divisibility

The most fundamental rejection is, of course, the one that the entire doctrine of minimum parts represents: the rejection of Aristotle’s conclusion that all continuous magnitudes are infinitely divisible. Aristotle’s position in Physics Book VI is that continuity requires infinite divisibility — that the concept of a continuum is incoherent unless division can always proceed further. Epicurus denies this, and his denial is grounded in the positive argument from Letter to Herodotus sections 56-57: an infinite number of parts, however small, must sum to an infinite magnitude; since no finite body is infinitely large, no finite body can have an infinite number of parts; therefore division must reach a minimum.

This argument is not a response to Aristotle’s formal argument about continuity so much as an independent positive argument for why continuity cannot be infinitely divisible on physical grounds. Epicurus is not trying to beat Aristotle at his own game of formal geometry. He is appealing to the canonical standard: what must be the case, given what sensation establishes about the finite sizes of finite physical bodies? The answer is that infinite divisibility is physically impossible, regardless of what the formal geometry of continuous magnitudes might seem to require. The canonical criterion overrides the geometric argument.

The Status of Mathematical Boundaries

Furley identifies another point of explicit departure. In Letter to Herodotus 58, Epicurus describes the minimum parts as units that are “not touching part to part” in the arrangement that constitutes a continuous atom. Furley reads this as Epicurus “clearly envisag[ing] another possibility altogether” for how partless entities can be arranged — one that is neither the “whole to whole” contact that Aristotle diagnosed in Democritean atoms nor the “part to part” contact that Aristotle’s own framework requires for genuine continuity. Furley argues that Epicurus was proposing that minimum parts, being genuinely extended units of measure rather than geometric points, stand in a sui generis relationship to each other within the atom that is not captured by Aristotle’s trichotomy of continuous/touching/consecutive.

Whether this is a successful philosophical response to Aristotle’s arguments about continuity is a question scholars have debated. Konstan is more optimistic than Furley on this point, arguing that the key move — giving the minimum part genuine physical extension in all three dimensions, making it a physical rather than a geometric entity — does enough work to escape the force of Aristotle’s formal argument, because Aristotle’s argument specifically targets dimensionless points, not extended minima. The debate between Furley and Konstan on this point represents one of the most technically productive areas of modern Epicurean scholarship.

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Part Five: The Broader Significance — Epicurus as Careful Philosopher

What the Episode Reveals About Epicurus’s Method

The detailed engagement with Aristotle’s criticism that the minimum part doctrine represents reveals something important about Epicurus’s philosophical method that is easily obscured by his reputation for dogmatism and his dismissive rhetoric toward predecessor philosophers. Whatever Epicurus said about his intellectual debts, the architecture of his atomic theory shows him doing exactly what a careful philosopher should do when confronted with a serious objection to a theory he has inherited: taking the objection seriously, identifying precisely which elements of the existing theory the objection successfully defeats, modifying those elements to address the objection, accepting the consequences that follow from the modification even when they are counterintuitive, and constructing a revised theory that preserves the framework’s explanatory power while closing the specific vulnerabilities the objection had identified.

The result — a theory of atoms composed of minimum parts, moving discontinuously through a granular space in indivisible units of time — is significantly more sophisticated than the Democritean theory it replaced. It is also, as the companion article “Let All Who Would Free Themselves From the False Claims of the Geometers Enter Here” argues, significantly more consistent with what modern physics has established about the structure of space and the behavior of matter at its finest scales.

The Canonical Standard as the Final Arbiter

There is one further point that deserves emphasis, because it distinguishes Epicurus’s engagement with Aristotle from mere capitulation to the more powerful philosophical argument. Epicurus accepted Aristotle’s conclusions about quantum motion not because Aristotle’s formal arguments were irrefutable on their own terms, but because those conclusions were consistent with — and in some respects required by — the canonical standard that Epicurus held as the final arbiter of all claims about physical reality.

The canonical standard, as developed in the companion article on Epicurean Canonics, requires that claims about the physical world be answerable to the evidence of sensation and experience. When Aristotle’s analysis of indivisible magnitudes in motion concluded that there can be no real differences in atomic speeds, this was a conclusion that Epicurus could accept because it was consistent with the physical evidence: we do not observe atoms directly, and the apparent differences in speed that we observe at the perceptible level are explicable through the interference effects of collisions in compound bodies without requiring that individual atoms move at different speeds. The conclusion neither contradicts sensation nor requires any entity that sensation cannot in principle reach.

By contrast, when Aristotle concluded that all continuous magnitudes are infinitely divisible, Epicurus rejected this conclusion — not primarily because Aristotle’s formal argument was flawed, but because the conclusion contradicts what the physical evidence requires. Finite physical bodies cannot be composed of an infinite number of parts without becoming infinitely large. That is the canonical check, and it overrides the geometric argument for infinite divisibility.

This is the Epicurean method in its most precise expression: use Aristotle’s analysis where it is consistent with the evidence, reject it where it contradicts the evidence, and in every case let the canonical criterion — not the formal power of the argument — be the final arbiter of what must be true about the physical world.

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Key Texts and Passages

Epicurus:

• Letter to Herodotus, sections 56—59 (the primary text for the minimum part doctrine); in Bailey, Epicurus: The Extant Remains (Oxford, 1926)
• Letter to Herodotus, sections 43—44 (atomic motion and collision)
• Letter to Herodotus, sections 61 (atomic weight and the direction of motion)

Aristotle:

• Physics Book VI (Zeta), chapters 1—2 (231a—232a): the foundational argument that continuous magnitudes cannot be composed of indivisibles; definition of continuity, contact, and consecutiveness
• Physics Book VI, chapters 4—5 (234b—236b): arguments about indivisible magnitudes in motion, establishing the quantization of time and spatial traversal
• Physics Book VI, chapter 9 (239b—240b): the Moving Rows paradox and its implications for atomic motion
• De Generatione et Corruptione Book I, chapter 8 (324b—326b): the contact problem; why Democritean partless atoms cannot properly be said to touch each other

Secondary Scholarship:

• David Furley, Two Studies in the Greek Atomists (Princeton University Press, 1967); Study I, “Indivisible Magnitudes” — the foundational modern analysis of how Epicurus’s motion theory responds to Aristotle’s Physics Book VI
• David Konstan, “Problems in Epicurean Physics,” Isis 70, No. 3 (1979), pp. 394—418 — especially Section II on atomic contact and the physical role of minimum parts as boundaries; Section I on the nature of atomic collision and discontinuous motion
• Gregory Vlastos, “Minimal Parts in Epicurean Atomism,” Isis 56, No. 2 (1965), pp. 121—147 — the complementary analysis of minimum parts as units of measure
• A.A. Long and D.N. Sedley, The Hellenistic Philosophers, 2 vols. (Cambridge University Press, 1987); section 9 (Epicurean physics: atoms, void, minimal parts) — texts and commentary
• David Sedley, “Epicurean Anti-Reductionism,” in J. Barnes and M. Mignucci (eds.), Matter and Metaphysics (Naples: Bibliopolis, 1988), pp. 295—327
• Richard Sorabji, Time, Creation and the Continuum (Cornell University Press, 1983) — on Aristotle’s treatment of continuity and the ancient debate about indivisible magnitudes
• Companion articles: “Let All Who Would Free Themselves From the False Claims of the Geometers Enter Here” and “The Continued Vitality of Epicurean Physics,” EpicurusToday.com

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