Clinical Investigation and Vision Sciences

See and to be seen.

Not so many years ago this was a mistake that brain scientists actually made: they succumbed all too often to the temptation to treat vision as if it were television — as if it were simply a matter of getting "the picture" from the eyes to the screen somewhere in the middle where it could be handsomely reproduced so that the phenomena of appreciation and analysis could then get underway. Today we realize that the analysis — the whatever you want to call it that composes, in the end, all the visual understanding — begins right away, on the retina; if you postpone consideration of it, you misdescribe how vision works.

The Greeks elaborated several theories of vision. According to the Pythagoreans, Democritus, and others vision is caused by the projection of particles from the object seen, into the pupil of the eye. On the other hand Empedocles, the Platonists, and Euclid held the strange doctrine of ocular beams, according to which the eye itself sends out something which causes sight as soon as it meets something else emanated by the object.