In this diagram were described ten circles, distinct from each other, but united by one circle, which was said to be the soul of all things, and was called “Leviathan.” This Leviathan, the Jewish Scriptures say, whatever they mean by the expression, was created by God for a plaything; for we find in the Psalms: “In wisdom have You made all things: the earth is full of Your creatures; so is this great and wide sea. There go the ships; small animals with great; there is this dragon, which You have formed to play therein.” Instead of the word “dragon,” the term “leviathan” is in the Hebrew.
This impious diagram, then, said of this leviathan, which is so clearly depreciated by the Psalmist, that it was the soul which had travelled through all things! We observed, also, in the diagram, the being named “Behemoth,” placed as it were under the lowest circle. The inventor of this accursed diagram had inscribed this leviathan at its circumference and centre, thus placing its name in two separate places. Moreover, Celsus says that the diagram was “divided by a thick black line, and this line he asserted was called Gehenna, which is Tartarus.”
Now as we found that Gehenna was mentioned in the Gospel as a place of punishment, we searched to see whether it is mentioned anywhere in the ancient Scriptures, and especially because the Jews too use the word. And we ascertained that where the valley of the son of Ennom was named in Scripture in the Hebrew, instead of “valley,” with fundamentally the same meaning, it was termed both the valley of Ennom and also Geenna. And continuing our researches, we find that what was termed “Geenna,” or “the valley of Ennom,” was included in the lot of the tribe of Benjamin, in which Jerusalem also was situated.
And seeking to ascertain what might be the inference from the heavenly Jerusalem belonging to the lot of Benjamin and the valley of Ennom, we find a certain confirmation of what is said regarding the place of punishment, intended for the purification of such souls as are to be purified by torments, agreeably to the saying: “The Lord comes like a refiner's fire, and like fullers' soap: and He shall sit as a refiner and purifier of silver and of gold.”
Source: Against Celsus (New Advent)