Intelligence is required to be able to know that a man knows not.

We cannot do without it, and yet we disgrace and vilify the same. It may be compared to a cage, the birds without despair to get in, and those within despair to get out.

A straight oar looks bent in the water. It matters not merely that we see a thing, but how we see it.

'As a man who knows how to make his education into a rule of life not a means of showing off; who can control himself and obey his own principles.' The true mirror of our discourse is the course of our lives.

My trade and art is to live.

My library is my kingdom, and here I try to make my rule absolute-shutting off this single nook from wife, daughter and society. Elsewhere I have only a verbal authority, and vague. Unhappy is the man, in my opinion, who has no spot at home where he can be at home to himself-to court himself and hide away.

I study myself more than any other subject. That is my metaphysics, that is my physics.