NOT EVEN THE LIGHT OF THE EYE IS TO BE CONSIDERED AS MEDIUM.
Project Gutenberg EPUB3 edition
Plotinus and Guthrie, Kenneth Sylvan
On the hypothesis that the soul remains within herself, while making use of the light (emanated from the eye) as a rod to reach the visible object, a very sharp perception would be caused by the resistance experienced by the light in its tension172 and sense-color. In so far as it is color, the light itself would possess the property of reflecting light. In this case, the contact would take place by a medium. But already before this the light has reached the object without any medium; so that the later contact operated by a medium would produce cognition by a sort of memory or reasoning—which is not the case.