Bacon
Let flattery, however, the bond-maid of vices, be far removed from friendship, since it is not only unworthy of a friend, but of a free man.
Cicero
How were friendship possible? In mutual devotedness to the Good and True: otherwise impossible, except as armed neutrality or hollow commercial league. A man, be the heavens ever praised, is sufficient for himself; yet were ten men, united in love, capable of being and of doing what ten thousand singly would fail in. Infinite is the help man can yield to man.
Carlyle
A real friend is one who will tell you of your faults and follies in prosperity, and assist you with his hand and heart in adversity.
Horace Smith
There be three sorts of friends: the first is like a torch we meet in a dark street; the second is like a candle in a lanthorn that we overtake; the third is like a link that offers itself to the stumbling passenger. The met torch is the sweet-lipped friend, which lends us a flash of compliment for the time, but quickly leaves us to our former darkness. The over-taken lanthorn is the true friend, which, though it promise but a faint light, yet it goes along with us as far as it can to our journey's end. The offered link is the mercenary friend, which though it be ready enough to do us service, yet that service hath a servile relation to our bounty.