Agreement in likes and dislikes — this, and this only, is what constitutes true friendship.

[Nam idem velle atque idem nolle, ea demum firma amicitia est.]

Catiline (108-62 BC) Roman politician [Lucius Sergius Catilina]

Quoted in Sallust, Catiline’s War [Bellum Catilinae], 20.4 (42 BC) [tr. Rolf]

Alt. trans.: "For to like the same things and to dislike the same things, only this is a strong friendship."