Episode 052 - More on Light, Vision, and Reflections
Date: 01/11/21
Link: https://www.epicureanfriends.com/thread/1822-episode-fifty-two-more-on-light-vision-and-reflections/
Summary
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Transcript
Section titled “Transcript”Welcome to Episode 52 of Lucretius Today. I’m your host Cassius and together with my panelists from the EpicureanFriends.com forum, we’ll walk you through the six books of Lucretius’ poem and discuss how Epicurean philosophy can apply to you today. But none of us are professional philosophers and everyone here is a self-taught Epicurean. We encourage you to study Epicurus for yourself and we suggest the best place to start is the book Epicurus and His Philosophy, by Canadian professor Norman DeWitt. For anyone who is not familiar with our podcast, please check back to Episode 1 for a discussion of our goals and our ground rules. If you have any question about that, please be sure to contact us at EpicureanFriends.com for more information. In today’s episode, we’re in Book 4 of the poem and we start with Latin text 230 and go to approximately 323. Now let’s join the discussion with Elaine reading today’s text.
Besides, since any figure we feel with our hands in the dark, we know to be the same we foresaw by day, and in the clearest light, the touch and sight must needs be moved by the same cause. And therefore, if we feel a quadrangular figure and distinguish its shape in the dark, what can present that shape to us in the light but its quadrangular image? The cause, therefore, of our sight must arise from the images, nor, indeed, can we distinguish anything without them. Now these images I’m speaking of are carried about every way and are thrown off and scattered on all sides. And therefore, it is, since with our eyes alone we are able to see, that which way soever we turn our eyes, the objects strike upon them in their proper form and color. The image, likewise, is the cause that we discover and takes care to satisfy us at what distance bodies,
From us. For as soon as it is emitted, it instantly thrusts forward and drives in the air that is placed between itself and the sight. This stream of air then glides to the eye, and as it were, grates gently upon the ball, and so passes through. Hence it is that we perceive how far things are distant from our sight. For the more air there is that is driven before the image, and the longer the stream of it that rubs upon the ball, the longer the interval of space between the object and the eye must be allowed to be. All this is done with the utmost celerity, for we see what the object is and know its distance in the same instance. Nor are we to think it at all strange in this case that the objects may be perfectly seen, and yet the images that singly strike the eye cannot themselves be discovered. For when the wind blows gently upon us, and its sharp cold pierces our bodies, We cannot discover it.
Nor can we distinguish the several particles of wind or cold that so affect us. But we are sensible of their whole strength together. We perceive their blows laid upon our bodies as if something were beating us, and made us feel the effects of its outward force upon us. And so when we strike a stone with our fingers, we touch the surface and outmost color of the stone, but then we feel nothing of the color or surface by our touch. We perceive no more than the hardness of the stone that lies within. And now learn why the image is always seen beyond the glass, for it certainly appears at a remote distance from us. For instance, when you are placed in an inner room and things are seen at a distance from you, when the door is open and gives you a clear prospect and allows you plainly to discover any object without, your sight in this case is formed, as I may say, by a double error. The error that lies within the door is the first, then the door is the second,
Then the middle between, and then the light without that rubs gently upon the eye, this is the other error. And at length the object is discovered. So when the image of the glass first flies off as it makes a passage to our sight, it strikes forward and drives in the error that lies between itself and the eye, so that we feel all this interjacent error before we see anything of the glass. But when we discover the glass, the image that is emitted from us instantly flies to us, and being reflected and sent back returns again to our sight, and forces the error that is before it, which is the reason that we perceive this interjacent error before the image that is seen by us. Now when two errors are driven, the image of the glass forcing on one, image reflected another, the interval must of necessity be more extended and even doubled. Hence it is that images appear not in the mirror image,
Which is the surface of the glass, but beyond it. And therefore we are not to wonder at all, that the images of things reflected to our sight, from the surface of the smooth glass by means of a double error, because it appears plainly that they are so. But more, that the part of the body that is the right side appears in the glass to be the left, because the image, when it strikes upon the surface of the glass, is not reflected again unchanged, but is turned a different way about. For instance, take a mask, made of clay, for it is dry, and dash it against a pillar or beam. If it preserves its figure entire, and appears inverted, only so that the face fills up the hollow, the event will be, that the right eye will now be the left, and the left the right, and then it may be contrived that the image shall pass from one glass into another, so that five or six images shall be reflected at once, and objects that are placed backwards in the inward part of the house, let them be ever so much, so much out of sight and.
The turnings ever so crooked be drawn out through the winding passages and by the placing of so many glasses be perfectly discovered. The image may be so transferred from one glass into another that it will change its left into its right but when it is again reflected from the second glass into the third it will resume its left part again and will continue to change in the same manner as it passes into all the glasses that follow but in glasses joined together in the convex figure of a pillar the side of the image reflected is returned so that the right part of the image answers to the right of the object or thing seen either because the image being transferred from one glass into another is reflected twice or that the image when it comes to us is turned about for that the face is turned about as it passes backwards we learn from the figure of the glass besides you would believe that the image moves with us and attends all our steps and imitates our gestures.
Because when you retire from any part of the glass, the image cannot be reflected from that part. For nature ordains that all images that are emitted from bodies be returned and reflected by equal angles. Elaine, thank you for reading 100 lines of the driest material we’ve probably ever read in the book. If someone were to pick up this book at this passage and start reading this material, they would throw it down as some of the most useless things they could possibly have read. So, it’s going to be up to us to get through this and relate it to reality. It’s funny to me that you have that reaction. I do, I do. Yeah, I’m curious. Why? Tell me your reaction. Well, it’s more of his attempt to understand what he’s seeing, what he’s observing, and to come up with explanations, which are not right. But it’s fascinating to me the way his mind works. I don’t find it drier than the other parts.
Well, I’m wondering why, why it strikes you that way. I think I lost the double air. You what? I think I lost the double air. The double air. That was cool. What do you think that means, Strong? You know, this is when you look at the mirror, no? So, then you have the air between… The air counts twice, from between your eye to the mirror, and back to the eye, no? Yeah, yeah. So, that’s why it’s a double air. Exactly. So, that one… It’s just that the theory comes up, that the light is pushing the air, and from the pressure of the air, we can sense the distance. That is nonsense. But, uh… But it’s creative, creative nonsense. For the time, it probably made a lot of sense. Yeah, yeah. Yeah. But the detail of the observation is again striking, so that tiny detail is added, and tries then to put in the context of the theory, which somehow makes sense. in this primitive education.
Isn’t that amazing, right? Right. I had a thought about this very first passage where he’s talking about being able to distinguish a shape without looking at it, which is a specific type of neurologic ability. Some people can lose that, where they’ll reach into a bag and feel of an object, and they’re not able to understand its shape with their hands. It’s hard to imagine that happening. Isn’t there a similar thing with people who are blind or regain their sight, and they can’t recognize images? Yes. The shapes and how to interpret the 3D. So I have a pediatric perspective on this. You know that stage that young babies go through where they want to put everything in their mouths? If you watch them real closely, they will kind of hold it out in front of.
Right in front of their face and look at it, put it in their mouth and mouth it and then look at it and mouth it. Parents think they’re teething, but the hypothesis of what they’re doing may be forming a correlation between vision, 3D vision and shape and that the mouth, not only the hands, is a great way to feel the shapes of objects in a lot of detail because our mouth, we have a lot of sensory nerve endings. And so they put this square or cube block, maybe in their mouth and fill all the edges with their tongues and then they take it out and they look at it. They’re making these, building these connections so that they really understand what it is they’re seeing because they felt it. I just think that’s fascinating. Well, I agree that it’s fascinating too, despite what I said,
You know, we’ll keep going then Elaine, before I then pull back to some of the more general comments I wanted to make today, let’s continue with the details here that you think are particularly interesting. Well, all this about the mirrors, I agree with Martin. I mean, it’s just, he really had so many observations and was trying to come up with a way to put them together, even though it was wrong. It’s just fascinating. But when he starts, he’s talking about all the different mirrors. I have a good friend, one of my closest friends who has the most hilarious sense of humor with her decorating. She has a beautiful house with all sorts of interesting objects, but she also has these little humor bits and she got this idea to decorate her fairly small guest bathroom with all sorts of mirrors. It has large, small, beautiful little ornaments. Ornate.
Mirrors. I’ve never seen so many mirrors in one little room. And so your image in the bathroom is everywhere. And it’s being reflected from one mirror to another. And that’s a really interesting experience. And I thought about her bathroom when he was talking about all these mirrors and things being reflected between them. Anyway, so just a little bit of humor there. Decorating idea for any of y’all. They want to play around. Will the text from this section be plastered on the wall in that room? Yes, it should be. laughing laughing.
Oh that’s a great idea well I have to admit that I’ve always found fascinating the I guess I think about it more in terms of the camera aimed at a television screen more so than I do just mirrors stacked together but the effect of bouncing things back and forth what am I trying to describe I don’t know how there’s a better way of saying it than what I just said but the apparently like infinite regress of images bouncing back and forth I think you can do that with a mirror and not just with a camera and a screen right you know when you point the camera at the screen and you start seeing yourself in the ever smaller images oh yeah it reminds me of Colbert that joke that he used to play on his show with all the pictures of himself and the reflections I don’t know Martin what’s the name does that have a name doing that I don’t know but we had in our bathroom we had two opposite mirrors so you could see they have practically an infinite number of times yeah get.
Smaller in first away so not really infinite but it’s a not limited series of your image yeah it’s humorous to me I wonder if Lucretius thought it was kind of funny yeah certainly the way he describes it so it’s done in a playful way yeah yeah sounds like it to me now is your feeling of dryness different a little bit a little bit if I were having to like I say explain this to somebody who just started in on this podcast I’d have to relate it back to something more general but that’s the problem that’s part of the deal is you just can’t reduce everything to a high level abstraction you’ve got to deal with details and explanations for why you come up with your conclusions and this is one of those many details that he works through all right well I can start to begin to transition once we get to next week we’ll start.
Solutions out of this but one of the things that I posted is a separate post it did it on the Facebook page as well was that just down the page or series of pages he starts talking about shadows and he talks about what a shadow might be and whether the light is being obscured light from the sun is being obscured or whatever and he makes this statement that I think is part of what brings it all home he says but in this case we are not in the least to allow that the eyes are deceived it is their business to discover only where the light and the shade are but to determine nothing whether the light be the same or the shadow be the same that moves one place to another or whether it be as we explained above it is the office of the mind and judgment to distinguish this for the eyes can know nothing of the nature of things and therefore you’re not to impute to them the failures of the mind you see.
And you have different theories about how these reflections are the eyes aren’t going to give you the answer as to how things work and they’re not going to give you a theory they’re going to give you observations from which you can construct an understanding but the eyes don’t do the understanding for example the very last statement that elaine read today besides you would believe that the image moves with us and all images that are emitted from bodies should be returned and reflected by equal angles well the conclusion that nature ordains that all images are emitted from bodies should be returned and reflected by equal angles is a conclusion and it may be right it may be wrong but only the eyes can tell us whether it’s right or wrong elaine the world of the and okay so my thoughts are i mean these days i don’t really conceive.
The nervous system as being so clearly separable so obviously you know the retina is not the prefrontal cortex but the peripheral nervous system and the sense organs without those the brain wouldn’t have anything to work with you know with nothing i mean if you had no senses at all not even touch i don’t know what you would think about i don’t know what thinking would be and you can do the same thing within the brain too that you can do between the brain and the eye so you could say well let’s say you you have a stroke and you lose your mathematical abilities or you can understand language but you can’t produce it you see there i mean so you can have a deficit in any part of the immune system so i was talking about the functions of the brain are as specific and you could talk about them separately and how they work together as much as as between the brain.
And the retina. So it gives you options how you want to divide the nervous system and talk about it. So in one way, you could talk about the sense of sight as being the combination of the eye, the optic nerve to the visual cortex. And then, you know, how we interpret it is, you know, those are other functions of the brain. But, the visual cortex does some of that automatically because of recognition and ability to integrate vision with our other senses like our tactile sense. So it’s a little bit more complicated, I guess I’m trying to say, than the way it’s presented here. But it’s not wrong to say one part of the nervous system can’t do the job of the entire nervous system and that our.
Decision to understand things really requires multiple parts of the nervous system, not just one. And definitely not just an eyeball. Martin or Charles, you guys have anything right now? No. Okay, well, since Elaine just mentioned the eyeball, let me pull out a section from the DeWitt book that I think is maybe helpful for putting some of it in perspective. I’m going to, let me just read a paragraph or two on page 204 of the book. Under a subsection entitled Vision, DeWitt says this. He says, In his explanation of vision, Epicurus sets himself in opposition to both Democritus and Plato. The latter had thought of the eyes as discharging little beams of light, which being homogeneous with the light of day, were capable of revealing the shapes and colors of external objects, conveying the impressions of them back to the consciousness of the observer.
The essential part of this theory is the homogeneity of the beam extending between eye and object, which ensures that red will be reported red and square square. In darkness, homogeneity is lacking and hence vision also. Although stimuli kinesis are spoken of, it is not made clear how the stimulus is delivered. And he’s talking about Plato there. And then DeWitt says, According to Democritus, the intervening air served the light. And he says, DeWitt says, according to Democritus, the purpose of a medium in vision being shaped in images by the pulsation of the atoms in an object. These images cause the sensation by falling upon the soft and moist surface of the people as upon a mirror. If the adoption of the air as a medium was occasioned by fear that atoms of solid bodies might wound the delicate surface of the eye, we may well understand why Epicurus in rejecting his master’s teaching dwells so positively upon the extreme.
Filminess of the idols, which he represents all bodies as discharging. At the same time that he overcomes this difficulty, he gives the opinion that the stream of idols thrown off by the object itself accounts more satisfactorily for the precision of the image impressed upon the eye as if by an engraved seal. So one of the background contexts we’re dealing with here is apparently that Democritus and Plato had had a very different position on how vision works. And it’s hard, this one, I mean, I think it was interesting, but it doesn’t, to me, have a lot more in it. So even though I didn’t find it dry, I’m not sure what else to say about it. Maybe this is just a shorter podcast, despite the length of the passage. Probably, Elaine, that’s what I’ll do. I’ll bring the podcast to a close pretty quickly here today on these points because I believe as soon as next week into the application of this information, information.
Then it gets back to the question of when can vision be trusted and when can it not be trusted? How do we check our observations against other visions and so forth? But while right now we’re in the middle of the details, the application isn’t there yet. Yeah, the only other thing that I noticed in here that I forgot to mention in the second paragraph. And so when we strike a stone with our fingers, we touch the surface and outmost color of the stone, but then we feel nothing of the color or surface by our touch. We perceive no more than the hardness of the stone that lies within. Is that feel nothing of the color or surface or the color of the surface? Because, of course, we feel texture. I’m thinking that he means that we just we don’t feel the we don’t feel the color. So I would like to say that, you know, just as our.
Anatomy. Act all feeling of the shape of an object or understanding of the three dimensional presentation of an object correlates with our vision. And for some people, you know, people who are blind in some cases are people who’ve trained themselves by a form of echo location. So they can hear a sound bouncing off objects and understand their shapes, which is amazing. So there’s not really the reason that we can’t feel color because the light has different wavelengths that’s coming off an object. So there’s no there could be an organism, let me say, that could have a nervous system that could detect differences between wavelengths of light and correlate that with the visual color. We just we don’t have that ability, but I don’t. I can’t think of any reason why.
It would be physiologically ruled out. Why it should be physiologically ruled out that we cannot touch color? Is that what you’re saying? Yeah, yeah. So we don’t have, I mean, so far as I know, humans don’t have that ability, but I don’t think that would be a fantastical thing to imagine there could be an organism that could develop that skill. Just like, you know, you have bats and they’re sonar and so on. It seems possible to me that there could be a tactile sense, which was so refined that it could detect differences in wavelengths of light. So I don’t know that any such thing exists, but I would just say, I don’t think it’d be beyond possibility that it could evolve. I think you’re right, Elaine. I think I could see the possibility that color at some extremely small level is a function of the shape of… Not the shape, but the wavelength of.
Light. The wavelength of light. Yeah. When I was a kid, I was convinced that I could tell the difference between differently colored objects of the same shape with my eyes closed. Then my dad, the physicist, said, no, you can’t. You know. What you can do is by experience, if there is a difference in texture, not directly the color, but is for example, if the pigments leaves the surface a different texture, that one you might be able to sense and then you correlate it. That means once you know this, you’ve trained for this, then you feel like you can sense the color. Yeah, right. Okay. Well, that would be interesting. pfft.
That was the only other thing I noticed here Martin at a atomic or very small level does the wavelength that’s reflected off of something have to do with the shape of the surface no no no this is a molecular thing alright well Charles what else do you have for today anything no it’s just one of those sections again where I prefer to listen okay hearing nothing further from anyone about the text today about to declare us finished for the day unless anybody has any final thoughts not me not me either okay very good alright well we’ll edit this podcast up and get it out and then we’ll come back to discuss images further next week so thanks everybody close for the day then bye thanks and bye.