TIMAEUS
© George MacDonald Ross, 1975–1999
This document is approximately 1 side of A4.
<c1> [45A] This is why [the gods] first made the head as a container, placing the face at the front, and putting inside it the organs necessary for the soul to have advance warning of things. [45B] They decreed that this should be the leading part of the body, and put it in its natural position at the front.
<c2> Of these organs, the first they constructed were luminous eyes, which they placed in the head for the following reason. They contrived to make a body out of the sort of fire which does not burn, but which provides a gentle light, similar to the light of day. They equipped us with a pure fire similar to it, and made it flow out of the eyes as a smooth and dense whole. [45C] They compressed the centres of the eyes in particular, so as to be impermeable to anything more coarse-grained, and so as to allow only this pure fire to pass through.
<c3> So when the visual stream is surrounded by full daylight, it flows out, since things which are similar are attracted to each other. The daylight and the visual stream become amalgamated into a homogeneous body along a straight line, from the eyes up to any point at which the visual stream from within meets something external which obstructs it. Since the whole body is affected in the same way because of its homogeneity, [45D] whatever it touches or is touched by, it transmits their motions along its whole length, right up to the soul, and gives rise to the sensation which we call ‘seeing’.
<c4> But when night falls, the external fire disappears, and the internal fire similar to it is cut off. The reason for this is that, when it emerges into something dissimilar, it is transformed and extinguished, since it is no longer of the same nature as the air surrounding it, which has no fire in it.
<c5> So it stops seeing, and also becomes conducive to sleep. [45E] This is because the gods gave the eyelids the natural function of protecting vision. The mechanism they devised was that when the eyelids are closed, they prevent the power of the inner fire from escaping. This power then disperses and evens out the inner motions, and this evening out brings about a state of rest.
<c6> If the state of rest is extreme, there follows almost dreamless sleep. But if some of the more forceful motions still remain, depending on what they are and where they are, [46A] they produce images of a certain nature and vividness, which are copied internally, and remembered by the dreamer when they wake up out of the dream.