Soul and Reproduction

One of Schopenhauer's fundamental theses is that sexual pleasure is Nature's means to stimulate Reproduction.  On that basis, the long and continuing tradition of treating sexual desire as a merely personal phenomenon is erroneous; rather, it a manifestation, in a Person, of a Species drive.  But, despite being the prototype of a critic of Empiricism, Plato takes sexual desire at face value, classifying it as one of the drives of the Appetitive portion of the Person-Soul.  He thereby misses an opportunity to systematically link the Person-Soul to a Polis-Soul, a World-Soul, or to any other trans-personal Soul, from which different concepts of Happiness and Justice might be developed.