All unnecessary vows are folly, because they suppose a prescience of the future, which has not been given us.

Economy is the parent of integrity, of liberty, and of ease, and the beauteous sister of temperance, of cheerfulness and health.

He that travels in theory has no inconveniences.

The truly strong and sound mind is the mind that can embrace equally great things and small.

The main of life is composed of small incidents and petty occurrences; of wishes for objects not remote, and grief for disappointments of no fatal consequence.

In lapidary inscriptions a man is not upon oath.

He that can swim needs not despair to fly; to swim is to fly in a grosser fluid, and to fly is to swim in a subtler. We are only to proportion our power of resistance to the different density of matter through which we are to pass. You will be necessarily upborne by the air if you can renew any impulse upon it faster than the air can recede from the pressure.