We know more about the movement of celestial bodies than about the soil underfoot.

He who does not understand the supreme certainty of mathematics is wallowing in confusion.

One has no right to love or hate anything if one has not acquired a thorough knowledge of its nature. Great love springs from great knowledge of the beloved object, and if you know it but little you will be able to love it only a little or not at all.

I have discovered that a screw-shaped device such as this, if it is well made from starched linen, will rise in the air if turned quickly.

Reprove your friend in secret and praise him openly.

Movement will fail sooner than usefulness.

The good painter must paint two things: a person and the essence of his soul.