1. Plato, ;
2. Aristotle, Books VIII–IX
3. Lucretius, , Book IV
4. Augustine, ; XIV; I
5. Aquinas, I–II, Questions 26–28
6. Dante, , ; Vita Nuova
7. Montaigne, , "Of Friendship"
8. Spinoza, , Parts III–V
9. Rousseau, , Book V; La Nouvelle Héloïse
10. Freud, ; Three Essays on the Theory of Sexuality