PLATO

Sensation awakes intellect. The reality behind phainomena, how is it revelated if it do not appear? Substance can only be thought if it become appearance: being = appearance, and man is measure of all things, of the existence, etc.

Error of Protagoras was in attributing the measure of things to individual as not‑plural rather than to individual as individual.

Knowledge (says Grote) is a bi‑polar, bi‑lateral phaenomenon.

The reason of a thing is that which explains it, that which accords being and thought. [...]