Paternity is based anyhow only upon conviction: I am convinced, therefore, I am the father.

And here, poor fool, with all my lore I stand no wiser than before.

What we agree with leaves us inactive, but contradiction makes us productive.

Excellence is rarely found, more rarely valued.

I could never have known so well how paltry men are, and how little they care for really high aims, if I had not tested them by my scientific researches. Thus I saw that most men only care for science so far as they get a living by it, and that they worship even error when it affords them a subsistence.

No one knows what he is doing so long as he is acting rightly; but of what is wrong one is always conscious.

[W]hat counts is that one perceives excellence and dares to give it expression, which sounds little but is in fact a great deal.