Protagoras

There are two sides to every question.

Let us hold our discussion together in our own persons, making trial of the truth and of ourselves.

No intelligent man believes that anybody ever willingly errs or willingly does base and evil deeds; they are well aware that all who do base and evil things do them unwillingly.

Man is the measure of all things.

No intelligent man believes that anybody ever willingly errs or willingly does base and evil deeds; they are well aware that all who do base and evil things to them unwillingly.

As to gods, I have no way of knowing either that they exist or do not exist, or what they are like.

The Athenians are right to accept advice from anyone, since it is incumbent on everyone to share in that sort of excellence, or else there can be no city at all.

Many things prevent knowledge including the obscurity of the subject and the brevity of human life