We should be aware than when attributing a concept to the Greeks we dont fall into the speculative trap of "who said or did this first",as this is mostly a notion of our times and one that has led to many misinterpretations.The only reason Empedocles is attributed this theory of the four roots is because he presents us with the first extant evidence for it,but by no means was it peculiar to him.It was a world conception held in general among the Greks;a basic model of interpreting the world,as seen in the Hippocratic writers and until Aristotle.Though the latter was aware of the determinism this theory led to,he nevertheless repeated it.The Alchemists(originally Hermetists)made this theory their cardinal doctrine only because it was so widely held as true(right into the modern age until Lavouazie).But in general we should note that the Greeks never thought about "copyrights"or "mental rights" when it came to searching the truth behind things!