Tischendorf lays much stress on the evidence of Hippolytus in coupling together the names of Ptolemæus and Heracleon with that of Valentinus; similar testimony of the same writer, fully confirming the above statement of Irenæus, will, therefore, have the greater force. Hippolytus says that the Valentinians differed materially among themselves regarding certain points which led to divisions, one party being called the {220} Oriental and the other the Italian. "They of the Italian party, of whom is Heracleon and Ptolemæus, say, &c.... They, however, who are of the Oriental party, of whom is Axionicus and Bardesanes, maintain," &c.(1) Now, Ptolemæus and Heracleon are here quite clearly represented as being contemporary with Axionicus and Bardesanes, and without discussing whether Hippolytus does not, in continuation, describe them as all living at the time he wrote,(2) there can be no doubt that some of them were, and that this evidence confirms again the statement of Irenæus. Hippolytus, in a subsequent part of his work, states that a certain Prepon, a Marcionite, has introduced something new, and "now in our own time [------] has written a work regarding the heresy in reply to Bardesanes."(3) The researches of Hilgenfeld have proved that Bardesanes lived at least over the reign of Heliogabalus (218--222), and the statement of Hippolytus is thus confirmed.(4) Axionicus again was still flourishing when Tertullian wrote his work against the Valentinians {221} (201--226). Tertullian says: "Axionicus of Antioch alone to the present day (ad hodiernum) respects the memory of Valentinus, by keeping fully the rules of his system."(1) Although on the whole they may be considered to have flourished somewhat earlier, Ptolemæus and Heracleon are thus shown to have been for a time at least contemporaries of Axionicus and Bardesanes.(2) Moreover, it is evident that the doctrines of Ptolemæus and Heracleon represent a much later form of Gnosticism than that of Valentinus. It is generally admitted that Ptolemæus reduced the system of Valentinus to consistency,(3) and the inconsistencies which existed between the views of the Master and these later followers, and which indicate a much more advanced stage of development, are constantly pointed out by Irenæus and the Fathers who wrote in refutation of heresy. Origen also represents Heracleon as amongst those who held opinions sanctioned by the Church,(4) and both he and Ptolemæus must indubitably be classed amongst the latest Gnostics.(5) It is clear, therefore, that Ptolemæus and Heracleon were contemporaries of Irenæus(6) at the time he composed his work against Heresies (185--195), both, and especially {222} the latter, flourishing and writing towards the end of the second century.(1)