Already in the Odyssey three who are surpassingly guilty detach themselves from the grey crowd of the shades who lead an uncertain life in Hades—Tityus, Tantalus and Sisyphus.[427] All three committed grave assaults on the gods, who in revenge condemned them to eternal torture: the gigantic body of Tityus is unceasingly gnawed by vultures; Tantalus is plunged in a pond the water of which flees from his eager lips, while above him is a tree of which the fruit escapes from his hand as he wishes to seize it; Sisyphus unendingly rolls to the top of a hill a rock which always tumbles back down the slope. These souls, in order that their suffering may be more cruelly felt, have in Hades a vitality beyond that of the common run of the dead, who are pale, flimsy, half animate phantoms.[428] To this Homeric triad of sufferers especially chastised by the divinity, further unhappy souls, whom an inexpiable crime had vowed to everlasting pains, were afterwards added: Ixion turning on the wheel to which he was fixed, Theseus and Pirithous enchained, the Danaïdes carrying water in a leaking vessel, and others. Thus was formed a group of legendary personalities whose crimes and punishments came to be the traditional themes of every description and representation of Tartarus in poetry and art until the downfall of paganism. But these convicted souls were no longer conceived, as they were by Homer, to be exceptional offenders on whom the gods avenged a personal insult. They had come to be the prototypes of men who, for like faults, would be similarly chastised, the terrible examples of the lot which divine wrath reserved for all who provoked it. They were explained as the incarnations of the different passions and vices, the representatives of the various classes of sinners on each of which a determined punishment was inflicted. The first authors of this new conception seem to have been the Orphic and Pythagorean theologians. Homer names only one class of criminals whom the Erinyes torture beneath the ground, the perjurers. But here again the motive of the punishment is a direct provocation of the gods; by the formula of execration which ended their oath, the perjurers had surrendered themselves to divine vengeance, if they broke their faith; and this is why a place apart among the sufferers of the underworld was always kept for them.