So different are the colors of life, as we look forward to the future, or backward to the past; and so different the opinions and sentiments which this contrariety of appearance naturally produces, that the conversation of the old and young ends generally with contempt or pity on either side.

The safe and general antidote against sorrow is employment.

He that travels in theory has no inconveniences.

They who look but little into futurity, have, perhaps, the quickest sensation of the present.

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

The complaint, therefore, that all topicks are preoccupied, is nothing more than the murmur of ignorance or idleness, by which some discourage others, and some themselves; the mutability of mankind will always furnish writers with new images, and the luxuriance of fancy may always embellish them with new decorations.

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.