The earliest reliable evidence for vegetarian theory and practice in Greece dates from the 6th century BC. The Orphics, a religious movement spreading in Greece at that time may have practiced vegetarianism. It is unclear whether the Greek religious teacher Pythagoras actually advocated vegetarianism and it is more likely that Pythagoras only prohibited certain kinds of meat. Later writers presented Pythagoras as prohibiting meat altogether. Eudoxus of Cnidus, a student of Archytas and Plato, writes that "Pythagoras was distinguished by such purity and so avoided killing and killers that he not only abstained from animal foods, but even kept his distance from cooks and hunters".