The firmest friendship is based on an identity of likes and dislikes.

The saying proposes that the most durable friendships rest on shared judgments—what two people admire, desire, and reject. “Likes and dislikes” implies more than common hobbies; it points to a deeper alignment of values and moral sensibilities. In Sallust’s political-historical world, alliances often formed around common interests and enmities, and concord could be strengthened as much by shared opposition as by shared affection. Read charitably, the line underscores friendship as a kind of ethical harmony; read skeptically, it hints that bonds may be cemented by factionalism—unity created through mutual hostility toward the same targets.