One of the most influential of Aristotle's ideas, the idea that the heavenly bodies consist of a fifth element distinct from the four earthly elements (earth, water, air, and fire) is widely believed to have been introduced to the world for the first time in Aristotle's lost dialogue De Philosophia. This assumption has created a host of problems which have not yet been solved.
Hahm, David E., "Aristotle's De Philosophia and the Introduction of the Fifth Element" (1971). The Society for Ancient Greek Philosophy Newsletter. 191.