To explain all nature is too difficult a task for any one man or even for any one age. 'Tis much better to do a little with certainty, and leave the rest for others that come after you, than to explain all things by conjecture without making sure of anything.

Necessity is the mistress and guide of nature.

Human subtlety will never devise an invention more beautiful, more simple or more direct than does nature because in her inventions nothing is lacking, and nothing is superfluous.

Here forms, here colours, here the character of every part of the universe are concentrated to a point; and that point is so marvellous a thing ... Oh! marvellous, O stupendous Necessity - by thy laws thou dost compel every effect to be the direct result of its cause, by the shortest path. These are miracles.

Necessity is the theme and the inventress, the eternal curb and law of nature.

Vitality and beauty are gifts of Nature for those who live according to its laws.