Comment by rck

This is fun. But the bit at the beginning about philosophy is not correct. Parmenides did not believe in what we would call essences, but really did believe that nothing ever changes (along with his fellow Eliatic philosopher Zeno, of paradox fame). The idea that change is an illusion is pretty silly, and so Plato and especially Aristotle worked out what's wrong with that and proposed the idea of _forms_ in part to account for the nature of change. Aristotle extended Plato's idea and grounded it in material reality which we observe via the senses, and that's where the concept of essence really comes from - "essence" comes from the Latin "essentia" which was coined to deal with the tricky Greek οὐσία (ousia - "being") that Aristotle uses in his discussions of change.