Man is the measure of all things, of things that are that they are, and of things that are not that they are not.
ProtagorasAbout the gods I have no means of knowing either that they exist or that they do not exist or what they are to look at. Many things prevent my knowing. Among others, the fact that they are never seen.
ProtagorasMan is the measure of all things, of the reality of those which are, and of the unreality of those which are not.
Protagoras