Tell me what company you keep, and I'll tell you what you are.

Miguel de Cervantes

A friend is, one might say, a secondself.

Cicero

Trusting no man as his friend, he could not recognize his enemy when the latter actually appeared.

Nathaniel Hawthorne

It is a great confidence in a friend to tell him your faults; greater to tell him his.

Benjamin Franklin

Friendship is a disinterested commerce between equals.

Oliver Goldsmith