So the “liquidissimus æther” of the Epicurean Lucretius (v. 501), “Suos ignes fert;” i.e. the fiery stars are of the nature of the element in which they move.  cf. the Stoic Manilius i. 149, “Ignis in æthereas volucer se sustulit oras summaque complexus stellantis culmina cœli, Flammarum vallo naturæ mœnia fecit.”