Because of Diamond, I have had to begin much of the work afresh. I will not, however, rid myself of her, nor even punish her. She knew not what she was doing, and that which she did was for my protection and for love of my person. Her place remains at my side or against my feet when I lie abed.

To any action there is always an opposite and equal reaction; in other words, the actions of two bodies upon each other are always equal and always opposite in direction.

All knowledge and understanding of the Universe was no more than playing with stones and shells on the seashore of the vast imponderable ocean of truth.

To explain all nature is too difficult a task for any one man or even for any one age

I consider my greatest accomplishment to be lifelong celibacy.

The seed of a tree has the nature of a branch or twig or bud. It is a part of the tree, but if separated and set in the earth to be better nourished, the embryo or young tree contained in it takes root and grows into a new tree.

His epitaph: Who, by vigor of mind almost divine, the motions and figures of the planets, the paths of comets, and the tides of the seas first demonstrated.