The Timaeus of Plato

E] TIMAIO2. 249
varieties of which it is our part to classify.
To these we have
given the name of colours, which consist of a flame streaming off
from every object, having its particles so adjusted to those of
the visual current as to excite sensation. We have already set
forth the causes which gave origin to vision: thus therefore it
will be most natural and fitting for a rational theory to treat of
the question of colours. The particles which issue from outward
objects and meet the visual stream are some of them smaller,
some larger, and some equal in size to the particles of that
stream. Those of equal size cause no sensation, and these we
call transparent; but the larger and smaller, in the one case by
contracting, in the other by dilating it, produce effects akin to
the action of heat and cold on the flesh, and to the action on
the tongue of astringent tastes and the heating sensations which
we termed pungent. These are white and black, affections
identical with those just mentioned, but occurring in a different
class and seeming to be different for the causes aforesaid. We
must then classify them as follows. What dilates the visual
stream is white, and the opposite thereof is black. A swifter
motion belonging to a different kind of fire, which meets and
colours produced are light and bright; if by sensibles excite sensation. Stallbaum,
they are larger and compress the stream, following Stephanus, understands etceivuv
the colours tend to be dark. to refer to deppa and ^vxpa, ffrpvtpvd and
dva