Few men have imagination enough for reality.

I am the Spirit that denies.

Love does not rule; but it trains, and that is more.

A mathematician is only perfect insofar as he is a perfect man, sensitive to the beauty of truth.

As for solitude, I cannot understand how certain people seek to lay claim to intellectual stature, nobility of soul and strength of character, yet have not the slightest feeling for seclusion; for solitude, I maintain, when joined with a quiet contemplation of nature, a serene and conscious faith in creation and the Creator, and a few vexations from outside is the only school for a mind of lofty endowment.

True art can only spring from the intimate linking of the serious and the playful.

Sceptics are yet the most credulous.