Although it might be appropriate for Socrates and minds of his stature to acquire virtue through reason, the human race would long ago have ceased to exist, if its preservation had depended solely on the reasonings of its members.
Gist of Idea
Rational morality is OK for brainy people, but ordinary life can't rely on that
Jean-Jacques Rousseau (Discourse on the Origin of Inequality , Part I)
He takes our natural compassion to be the basis of morality. Hume combines that with a natural social prudence. Apes live successfully together in groups, without a Socrates. See MacIntyre on the failure of reasoned morality.
Rousseau,Jean-Jacques: 'The Basic Political Writings', ed/tr. Cress,Donald A. [Hackett 1987], p.55