Quite often good things have hurtful consequences. There are instances of men who have been ruined by their money or killed by their courage.

Doubt is the beginning of wisdom

If you prove the cause, you at once prove the effect; and conversely nothing can exist without its cause.

Great men are always of a nature originally melancholy.

Excellence is an art won by training and habituation.

There is no great genius without a mixture of madness.

All human happiness and misery take the form of action.