Against Celsus 6.26

and according to the saying that punishments take place around Jerusalem for those who are refined, who have taken into the very substance of their soul the things that come from wickedness, which is somewhere called, figuratively, lead; that is why in Zechariah lawlessness sat upon “a talent of lead.” But all that might be said on this subject is neither for everyone nor for the present occasion. Nor is it without danger to commit the clear explanation of such things to writing, since the many need no further teaching than that about the punishment of sinners. For it is not useful to go beyond this, because of those who are barely restrained, even by fear of eternal punishment, from at least some of the flood of wickedness and the sins that come from it. So neither the diagram nor Celsus knows the teaching about Gehenna; for otherwise those people would not make much of pictures and diagrams as though they presented the truth by them, nor would Celsus, in his treatise against Christians, have put among his accusations against Christians things that are in no way said by Christians but by some people who perhaps no longer even exist, having entirely died out and dwindled to a very few who can easily be counted. And just as it is not the business of those who follow Plato's philosophy to make a defence for Epicurus and his impious doctrines, so it is not ours to defend what is in the diagram and what Celsus says against it. Therefore we leave aside what Celsus said about these matters as superfluous and pointless; for we would accuse those who are held by such teachings more than Celsus does.