Complete Works of Plutarch — Volume 3: Essays and Miscellanies
Chapter 46
The Stoics say that the stars are of a circular form, like as the sun, the moon, and the world. Cleanthes, that they are of a conical figure. Anaximenes, that they are fastened as nails in the crystalline firmament; some others, that they are fiery plates of gold, resembling pictures.