Every action needs to be prompted by a motive.

Movement will fail sooner than usefulness.

A day will come in which men will look upon an animal's murder the same way they look today upon a man's murder.

I have been impressed with the urgency of doing. Knowing is not enough; we must apply. Being willing is not enough; we must do.

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

The vine that has grown old on an old tree falls with the ruin of that tree, and through that bad companionship must perish with it.

You should prefer a good scientist without literary abilities than a literate one without scientific skills