ARISTOTLE HAS TO DEPEND ON QUINTESSENCE.
On the contrary, in the system of Aristotle, the immutability of the stars is easily explained, but only after accepting his theory of a fifth element (the quintessence[205]). If, however, it be rejected, it would be impossible to demonstrate that the heaven, let alone its parts, the sun and the stars, do not perish, while (as Aristotle does) we regard the body of the heaven as being composed of the same elements as terrestrial animals.