Ammianus Marcellinus Res Gestae 22.13.3

[3] It was said, however, though on very slight evidence, that the cause of the burning of the temple was this: the philosopher Asclepiades, whom I have mentioned in the history of Magnentius, ¹ when he had come to that suburb ² from abroad to visit Julian, placed before the lofty feet of the statue a little silver image of the Dea Caelestis, ³ which he always carried with him wherever he went, and after lighting some wax tapers as usual, went away. From these tapers after midnight, when no one could be present to render aid, some flying sparks alighted on the woodwork, which was very old, and the fire, fed by the dry fuel, mounted and burned whatever it could reach, at however great a height it was.