Ptolemaeus and Heracleon, representing the Western branch, took one side, while Axionicus and Bardesanes, representing the Eastern, took the other.

Ptolemaeus and Heracleon were both, we know, contemporaries of Irenaeus, so that the quotation was used among the Valentinians at least in the time of Irenaeus, and very possibly earlier, for it usually takes a certain time for a subject to be brought into controversy.

We must thus take the _terminus ad quem_ for the quotation not later than 180 A.D.How much further back it goes we cannot say, but even then (if the Valentinian text is correctly preserved by Hippolytus) it presents features of corruption.
That the Valentinians made use of unwritten sources as well as of written, and that they possessed a Gospel of their own which they called the Gospel of Truth, does not affect the question of their use of the Synoptics.

For these very same Valentinians undoubtedly did use the Synoptics, and not only them but also the fourth Gospel.

It is immediately after he has spoken of the 'unwritten' tradition of the Valentinians that Irenaeus proceeds to give the numerous quotations from the Synoptics referred to above, while in the very same chapter, and within two sections of the place in which he alludes to the Gospel of Truth, he expressly says that these same Valentinians used the Gospel according to St.John freely (plenissime) [Endnote 203:1].