It is beyond a doubt that all our knowledge that begins with experience.

It is not necessary that whilst I live I live happily; but it is necessary that so long as I live I should live honourably.

Seek not the favor of the multitude; it is seldom got by honest and lawful means. But seek the testimony of few; and number not voices, but weigh them.

By a lie, a man... annihilates his dignity as a man.

Out of the crooked timber of humanity, no straight thing was ever made.

Science is organized knowledge. Wisdom is organized life.

A categorical imperative would be one which represented an action as objectively necessary in itself, without reference to any other purpose.