The alchemists themselves, of course, claimed for their art the highest antiquity. Zosimus of Panopolis, who seems to have written in the third century, says that the fallen angels instructed men in alchemy as well as in the other arts, and that it was the divine and sacred art of the priests and kings of Egypt, who kept it secret. We also have an address of Isis to her son Horus repeating the revelation made by Amnael, the first of the angels and prophets. To Moses are ascribed treatises on domestic chemistry and doubling the weight of gold.[899] The manuscripts of the Byzantine period discuss what “the ancients” meant by this or that, or purport to repeat what someone else said of some other person. Zosimus seems fond of citing himself in the texts reproduced by Berthelot, so that it may be questioned how much of his original works has been preserved. Hermes is often cited by the alchemists, although no work of alchemy ascribed to him has reached us from this early period. To Agathodaemon is ascribed a commentary on the oracle of Orpheus addressed to Osiris, dealing with the whitening and yellowing of metals and other alchemical recipes. Other favorite authorities are Ostanes, whom we have elsewhere heard represented as the introducer of magic into the Greek world, and the philosopher Democritus, whom the alchemists represent as the pupil of Ostanes and whom we have already heard Pliny charge with devotion to magic. Seneca says in one of his letters that Democritus discovered a process to soften ivory, that he prepared artificial emerald, and colored vitrified substances. Diogenes Laertius ascribes to him a work on the juices of plants, on stones, minerals, metals, colors, and coloring glass. This was possibly the same as the four books on coloring gold, silver, stones, and purple ascribed to Democritus by Synesius in the fifth, and Syncellus in the eighth, century. More recent presumably than Ostanes and Democritus are the female alchemists, Cleopatra and Mary the Jewess, although one text represents Ostanes and his companions as conversing with Cleopatra. A few of the spurious works ascribed to these authors may have come into existence as early as the Hellenistic period, but those which have reached us, at least in their present form, seem to bear the marks of the Christian era and later centuries of the Roman Empire, if not of the early medieval and Byzantine periods. And those authors whose names seem genuine: Zosimus, Synesius, Olympiodorus, Stephanus, are of the third, fourth and fifth centuries, at the earliest. [Sidenote: Close association of Greek alchemy with magic.]