If a man's wit be wandering, let him study the mathematics; for in demonstrations, if his wit be called away never so little, he must begin again.

Aristotle... a mere bond-servant to his logic, thereby rendering it contentious and well nigh useless.

Since my logic aims to teach and instruct the understanding, not that it may with the slender tendrils of the mind snatch at and lay hold of abstract notions (as the common logic does), but that it may in very truth dissect nature, and discover the virtues and actions of bodies, with their laws as determined in matter; so that this science flows not merely from the nature of the mind, but also from the nature of things.

The general root of superstition is that men observe when things hit, and not when they miss, and commit to memory the one, and pass over the other.

As the births of living creatures at first are ill-shapen, so are all innovations, which are the births of time.

Nothing is to be feared but fear itself. Nothing grievous but to yield to grief.

I have often thought upon death, and I find it the least of all evils.