Leucippus and Zeno say, that it is a body and a fragment of the soul. Pythagoras, Plato, and Aristotle, that the spermatic faculty is incorporeal, as the mind is which moves the body; but the effused matter is corporeal. Strato and Democritus, that the essential power is a body; for it is like spirit.
Complete Works of Plutarch — Volume 3: Essays and Miscellanies · The Wunder Library — complete classics, free to read, with narration.