We ourselves introduce that order and regularity in the appearance which we entitle "nature". We could never find them in appearances had we not ourselves, by the nature of our own mind, originally set them there.

An action, to have moral worth, must be done from duty.

Experience without theory is blind, but theory without experience is mere intellectual play.

Nature, when left to universal laws, tends to produce regularity out of chaos.

Do the right thing because it is right.

The more we come in contact with animals and observe their behaviour, the more we love them, for we see how great is their care of the young.

Reason in a creature is a faculty of widening the rules and purposes of the use of all its powers far beyond natural instinct; it acknowledges no limits to its projects. Reason itself does not work instinctively, but requires trial, practice, and instruction in order gradually to progress from one level of insight to another.