Pliny addresses magic in Book XXX. He is critical of the Magi, attacking astrology, and suggesting that magic originated in medicine, creeping in by pretending to offer health. He names Zoroaster of Ancient Persia as the source of magical ideas. He states that Pythagoras, Empedocles, Democritus and Plato all travelled abroad to learn magic, remarking that it was surprising anyone accepted the doctrines they brought back, and that medicine (of Hippocrates) and magic (of Democritus) should have flourished simultaneously at the time of the Peloponnesian War.