Key Arguments

• He defines the transparent as a medium that is not intrinsically visible in itself but visible because of others' colors: 'There is, then, something transparent. And by transparent I mean what is indeed visible, although not intrinsically visible, simply speaking, but rather visible because of | 418 b 5 | the color of something else.'
• He identifies instances of the transparent and posits a common nature shared with the heavenly body: 'Air, water, and many solid bodies are of this sort. For it is not insofar as something is water or insofar as it is air that it is visible, but because there is a certain nature in it that is the same in both of them and in the [eternal] body above. 234'
• He defines light as the energeia of the transparent qua transparent: 'And light is the activity of this, of the transparent insofar as it is transparent.'
• He characterizes darkness as the potential state of the same medium and light as a kind of 'color' of the transparent: 'But whatever this is present in, so potentially | 418 b 10 | is darkness. For light is a sort of color of the transparent, when it is made actually transparent by fire or something of that sort, such as the body above.'
• He explicitly denies that light is itself fire, a body, or an effluence, and instead defines it as the presence of fire-like bodies in the transparent: 'What the transparent is, then, and what light is has been stated, namely, that it is not fire nor a body at all, nor an effluence from any body (for it would also be a body | 418 b 15 | in that case), but rather the presence of fire or something of that sort in the transparent.'
• He uses the contrariety of light and dark to reinforce this: 'For in addition to its not being possible for there to be two bodies in the same place at the same time, light also seems to be the contrary of dark. But dark is the lack of this sort of state in the transparent, so it is clear again that the presence of it is light.'

Source Quotes

There is, then, something transparent. And by transparent I mean what is indeed visible, although not intrinsically visible, simply speaking, but rather visible because of | 418 b 5 | the color of something else. Air, water, and many solid bodies are of this sort.

And by transparent I mean what is indeed visible, although not intrinsically visible, simply speaking, but rather visible because of | 418 b 5 | the color of something else. Air, water, and many solid bodies are of this sort. For it is not insofar as something is water or insofar as it is air that it is visible, but because there is a certain nature in it that is the same in both of them and in the [eternal] body above.

Air, water, and many solid bodies are of this sort. For it is not insofar as something is water or insofar as it is air that it is visible, but because there is a certain nature in it that is the same in both of them and in the [eternal] body above. 234 And light is the activity of this, of the transparent insofar as it is transparent. But whatever this is present in, so potentially | 418 b 10 | is darkness.

For it is not insofar as something is water or insofar as it is air that it is visible, but because there is a certain nature in it that is the same in both of them and in the [eternal] body above. 234 And light is the activity of this, of the transparent insofar as it is transparent. But whatever this is present in, so potentially | 418 b 10 | is darkness.

But whatever this is present in, so potentially | 418 b 10 | is darkness. For light is a sort of color of the transparent, when it is made actually transparent by fire or something of that sort, such as the body above. For one and the same [affection] also belongs to it.

For one and the same [affection] also belongs to it. 235 What the transparent is, then, and what light is has been stated, namely, that it is not fire nor a body at all, nor an effluence from any body (for it would also be a body | 418 b 15 | in that case), but rather the presence of fire or something of that sort in the transparent. For in addition to its not being possible for there to be two bodies in the same place at the same time, light also seems to be the contrary of dark.

For in addition to its not being possible for there to be two bodies in the same place at the same time, light also seems to be the contrary of dark. But dark is the lack of this sort of state in the transparent, so it is clear again that the presence of it is light. And so Empedocles is not correct, | 418 b 20 | and nor is anyone else who spoke in this way, that light travels and arrives at some time between the earth and what surrounds it, without our noticing it.

Key Concepts

• And by transparent I mean what is indeed visible, although not intrinsically visible, simply speaking, but rather visible because of | 418 b 5 | the color of something else.
• Air, water, and many solid bodies are of this sort.
• but because there is a certain nature in it that is the same in both of them and in the [eternal] body above. 234
• And light is the activity of this, of the transparent insofar as it is transparent.
• For light is a sort of color of the transparent, when it is made actually transparent by fire or something of that sort, such as the body above.
• it is not fire nor a body at all, nor an effluence from any body (for it would also be a body | 418 b 15 | in that case), but rather the presence of fire or something of that sort in the transparent.
• dark is the lack of this sort of state in the transparent, so it is clear again that the presence of it is light.

Context

Middle of II.7 (418b2–18), where Aristotle introduces and defines the transparent, light, and darkness within his hylomorphic physics of perception.