The subject has quite recently been treated in a monograph by the well-known writer Dr.Keim [Endnote 260:1], and, as there will be in this case no suspicion of partiality, I shall content myself with stating Dr.Keim's conclusions.
Origen himself, Dr.Keim thinks, was writing under the Emperor Philip about A.D.248.

But he regards his opponent Celsus, not as a contemporary, but as belonging to a past age (Contra Celsum, i.
8, vii.

11), and his work as nothing recent, but rather as having obtained a certain celebrity in heathen literature (v.

3).

For all this it had to be disinterred, as it were, and that not without difficulty, by a Christian (viii.