for flame could not be produced by them, nor of its own accord, but if fire were brought near to clothes steeped in naphtha they would at once burst into flame.  The reason of this is that the rays which fire sends forth fall harmlessly upon all other bodies, merely imparting to them light and heat; but when they meet with such as have an oily, dry humour, and thereby have a sympathy with the nature of fire, they easily cause them to catch fire.  It is a disputed question, however, how the naphtha is produced, though most writers conceive its combustible principle to be supplied by the greasy and fiery nature of the soil; for all the district of Babylonia is fiery hot, so that often barley is cast up out of the ground in which it is sown, as if the earth throbbed and vibrated with the heat, and during the hottest part of summer the inhabitants are wont to sleep upon leathern bags filled with water for the sake of coolness.  Harpalus, who was appointed governor of the district, took an especial delight in adorning the palace and the public walks with Greek flowers and shrubs; but although he found no difficulty with most of them, he was unable to induce ivy to grow, because ivy loves a cold soil, and the earth there is too hot for it.  These digressions, provided they be not too lengthy, we hope will not be thought tedious by our readers.

XXXVI.  When Alexander made himself master of Susa, he found in the palace forty thousand talents worth of coined money, besides an immense mass of other valuable treasure.  Here we are told was found five thousand talents weight of cloth dyed with Hermionic[411] purple cloth, which had been stored up there for a space of two hundred years save ten, and which nevertheless still kept its colour as brilliantly as ever.  The reason of this is said to be that honey was originally used in dyeing the cloth purple, and white olive oil for such of it as was dyed-white:  for cloth of these two colours will preserve its lustre without fading for an equal period of time.  Demon also informs us that amongst other things the Kings of Persia had water brought from the Nile and the Danube, and laid up in their treasury, as a confirmation of the greatness of their empire, and to prove that they were lords of all the world.

XXXVII.  As the district of Persis[412] was very hard to invade, both because of its being mountainous, and because it was defended by the noblest of the Persians (for Darius had fled thither for refuge), Alexander forced his way into it by a circuitous path, which was shown him by a native of the country, the son of a Lykian captive, by a Persian mother, who was able to speak both the Greek and the Persian language.  It is said that while Alexander was yet a child, the prophetess at the temple of Apollo at Delphi foretold that a wolf[413] should some day serve him for a guide when he went to attack the Persians.  When Persis was taken, a terrible slaughter was made of all the prisoners.  A letter written by Alexander himself is still extant, in which he orders that they should all be put to the sword, thinking this to be the safest course.  He is said to have found as much coined money here[414] as in Susa, and so much other treasure that it required ten thousand carts, each drawn by a pair of mules, and five thousand camels, to carry it away.