^ f. UBBARV - JScholarship - Johns Hopkins University

VISION 39
of an image in the eye by reflexion. They do not, however,
provide in their theory for these facts, viz. that {a) the real
magnitudes seen are not symmetrical with the reflected
magnitudes ; (b) it is impossible for a plurality of reflexions
to take place in the eye simultaneously with their contraries ;
(c) though movement, distance, and magnitude are visible
none of these reflects an image; {d) some animals, e. g.
those which have scales on the eyes, and those which live
in water, have no image reflected in the eye and yet they
see. Besides these points, if such reflexion were the
sufficient reason of seeing, many inanimate things would see;
for reflexion takes place in water, bronze, and many other
things. Anaxagoras also teaches that colours are all
reflected in one another, but a strong colour in a weak
rather than conversely; so that while either the strong
or the weak ought to see, yet a black eye should see better
than one of any other colour: and, in general, an eye of
weaker, better than one of stronger colour^. Wherefore
he describes the organ of seeing as being of the same hue
as night, and light as the cause of the reflexion of an image
in the eye. But, in the first place, we see light itself
without the need of such reflexion; and, in the next, we
see black colours just as well as white, though the former
do not contain light (which according to Anaxagoras is
needful to produce the reflected image) ^. Again, in the case
of other things (apart from optical reflexion), we see that
reflexion of images takes place in that which is brighter
and purer (than the object reflected); and, accordingly,
Anaxagoras himself declares that the membranes covering
the eyes are delicately fine and bright.'
§ 22. The object of vision: colour. 'As regards colours ^ „orasVno
^ ' The' weakest' colour, as would appear from this, is black according
to Anaxagoras and Theophrastus. This, therefore, represents all
other colours by reflexion.
" Some such word as dXXa or kuItoi seems to have been lost before
OVK exei in the sentence eireiTa ov8ev TjTTOv Ta peXava tS>v XevK&v ovk exei
(j)S>s. This, as it Stands in Wimmer's and Diels' texts = non minus
nigra quam alba lucem non kabent, makes no sense. I have translated
according to what I conceive the true reading.
' Theophr. de Sens. § 59 (Diels, Box., p. 516).