The only way to have a friend is to be one.

Happy is the house that shelters a friend

The only reward of virtue is virtue; the only way to have a friend is to be one

Better to be a nettle in the side of your friend than his echo.

A friend is a person with whom I may be sincere. Before him I may think aloud.

Consider what you have in the smallest chosen library: a company of the wisest and wittiest men that could be picked out of all civil countries in a thousand years.... The thought which they did not uncover to their bosom friend is here written out in transparent words to us, the strangers of another age.