An American monkey, after getting drunk on brandy, would never touch it again, and thus is much wiser than most men.

The remark uses a humorous comparison between human vice and animal learning. Darwin’s point is that some animals can form strong aversions after a single harmful experience (here, intoxication), while many humans repeatedly return to self-destructive habits despite knowing the consequences. The line also plays on Victorian anxieties about alcohol and moral self-control, turning the usual hierarchy—humans as wiser than animals—on its head. In the broader Darwinian frame, it suggests continuity between human and animal behavior while highlighting that “reason” does not automatically translate into better conduct; instinct, conditioning, and social habit can override knowledge.