It is presumed that there exists a great unity in nature, in respect of the adequacy of a single cause to account for many different kinds of consequences.

If you punish a child for being naughty, and reward him for being good, he will do right merely for the sake of the reward; and when he goes out into the world and finds that goodness is not always rewarded, nor wickedness always punished, he will grow into a man who only thinks about how he may get on in the world, and does right or wrong according as he finds advantage to himself.

Thrift is care and scruple in the spending of one's means. It is not a virtue and it requires neither skill nor talent.

cruelty to animals is contrary to man's duty to himself, because it deadens in him the feeling of sympathy for their sufferings, and thus a natural tendency that is very useful to morality in relation to other human beings is weakened.

I have no knowledge of myself as I am, but merely as I appear to myself.

Physicians think they do a lot for a patient when they give his disease a name.

If a man is often the subject of conversation he soon becomes the subject of criticism.