M. Tullius Cicero, Laelius on friendship
William Armistead Falconer, Ed.

[88] True, therefore, is that celebrated saying of Archytas of Tarentum, I think it was—a saying which I have heard repeated by our old men who in their turn heard it from their elders. It is to this effect: “If a man should ascend alone into heaven and behold clearly the structure of the universe and the beauty of the stars, there would be no pleasure for him in the awe-inspiring sight, which would have filled him with delight if he had had someone to whom he could describe what he had seen.” Thus nature, loving nothing solitary, always strives for some sort of support, and man's best support is a very dear friend.

[p. 197] 24. But though this same nature declares by so many utterances what she wishes, what she seeks, and what she ardently longs for, yet we somehow grow deaf and do not hearken to her voice. For varied and complex are the experiences of friendship, and they afford many causes for suspicion and offence, which it is wise sometimes to ignore, sometimes to make light of, and sometimes to endure. But there is one cause of offence which must be encountered in order that both the usefulness and loyalty of friendship may be preserved; for friends frequently must be not only advised, but also rebuked, and both advice and rebuke should be kindly received when given in a spirit of goodwill.