The painter who has no doubt about his own ability will attain very little.

The earth is moved from its position by the weight of a tiny bird resting upon it.

No human investigation can claim to be scientific if it doesn't pass the test of mathematical proof.

Threats alone, are the weapons of the threatened man.

The noblest pleasure is the joy of understanding.

You grow in reputation like bread in the hands of a child.

Nature never breaks her own laws.