The Gnostic heretics had appealed to the principles of Platonism to provide a philosophical justification for their doctrine that the elect soul must be liberated from the evil inherent in the material realm to escape to its true home and to enjoy the beatific vision. Their deep pessimism about this created order was not quite fairly deduced from the text of Plato, but there was a sufficient plausibility about the argument to make it look impressive. The Gnostic appeal to pagan philosophy did not tend to encourage the study of philosophy among those who feared Gnosticism as a corrupter of the truth. Philosophy came to seem like the mother of heresy. To Irenaeus of Lyons Gnosticism was a ragbag of heathen speculations with bits taken from different philosophers to dress out a bogus, anti-rational mythology. His successor as an anti-heretical writer, Hippolytus, whose mind was a curious mixture of scholarship and foolishness, wrote a lengthy refutation of the sects based on the presupposition that each sect had corrupted the authentic gospel by principles drawn from a pagan philosopher; he incidentally preserved thereby many fragments of classical philosophers like Heraclitus which would otherwise have been lost. Tertullian scornfully mocked those who 'advocate a Stoic or a Platonic or an Aristotelian Christianity'. It was a Gnostic thesis that faith needs supplementation by philosophical inquiries. 'What has Athens in common with Jerusalem?'