
“Agreement in likes and dislikes—this, and this only, is what constitutes true friendship.”
Idem velle atque idem nolle, ea demum firma amicitia est.
As quoted by Sallust (86 BC – c. 35 BC) in Catiline's War, Book XX, pt. 4 (trans. J. C. Rolfe).
Variant translations:
To like and dislike the same things, that is indeed true friendship.
To like the same things and to dislike the same things, only this is a strong friendship.