[Visible] and invisible [are] both the color and what can be described with an account but has no name.[1] Such things are glow-worms, heads of fishes, scales, eyes of hedgehogs, the shells of the sea creatures, which are visible not in light but in darkness. For the fiery thing which appears in darkness in these creatures does not seem to be color; for [in fact it is] characteristic of color to be seen in light; but what is fiery in these creatures is not visible in light.
Seeing is the transparency [deriving] from having air, which has the power to transmit colors, being itself colorless.
There are 4 differences among the visible things. For some of them are visible only in day, others only in night, others both in night and day, and others are by nature incompatible with darkness. For some of the visible things are colors, but others lack a name. Now colors can be seen only in day, but not in night at all. Among the things that are called 'bright', some are visible only in night, others only in day, and others both in night and day. For some of them are exceedingly bright, others dim, others intermediate. Now things which have a dim bright[ness] are only visible in night, such as glow-worms, scales, and the like; for their brightness does not appear in day, insofar as it is overcome by what is greater; furthermore, most of the stars [sc. are also so]. The intermediate [appear] in night and in day, such as the moon and some of the stars, like the morning star, when the sun is near the horizon and the morning star itself appears nearer the earth. Furthermore, also fire: for this, insofar as it is possible, makes the air perfect and leads its transparency toward its actualization, so that colors are shown in it, but it shows itself in the rest; its transparency does not lead toward actualization. Hence when we are in darkness we see it from far away, but [we cannot see] any of the colors near us. But in the day, however, fire appears as something bright, but it does nothing to the air because it has already been affected by the greater bright[ness]; and the bright[ness] of the moon appears in day because it is not quite obscure. By contrast those things that are exceedingly bright appear only in the day, like the sun, because it is also the cause of the day's light.