I've been reading Aristotle's treatsie about the soul of living things or "On the Soul (De Anima)".
Now Aristole was a student of Plato, but I think it would be incorrect call this work Platonic, because he forwards his independently developed ideas, not just ones taught to him by Plato.
While Plato does touch on the soul in his works, Aristotle explores the idea of a soul as it applies to other living things such as animals and plants. I think that in itself makes "De Anima" unique, rather than a regurgitation of Plato's work.
That's my opinion anyway.