18 aeon?,,not sure unless i missed it. i notice searching for the books of irenaeus online there are several sources for it. in most they just begin at book one,others begin with the preface irenaeus wrote in his letters. in the preface he valentinus as the main subject. that is he was the one who had a school and taught gnostism. but then he explains later and then brakes it down in the later chapters that there were other branches that sprang off valentinus. i.e. Marcus,Simon mangus,ect..In the later chapters he shows that the branches "deviated in doctrine" that is "the doctrine valentinus was teaching,they modified as they spread out teaching". Markus(in later chapters) Irenaeus states would take certain names for instance sophia/wisdom and take s.o.p.h.i.a.,,,,and begin with the letter (s),(aleph in greek),,,and say other words/ names that began with these letters,then the second letter of the same ect.,,,"so it's infinite" according to the teaching of Marcus showing the infinite name of god.Marcus was also known to use "drugs" on his followers,as well as magic/tricks.Back to Valentinus, in the first chapter of book 1 A/H,,Irenaeus gives the explanation of the "aeons" as to the way "Valentinus" reckoned them. But in the preface he(Irenaeus) states that he spoke "a barbaric dialect because he was from the Keltae,irenaeus not valentinus,Irenaeus was Keltae. So then there are "many branches of the gnostics",,,lets narrow it down to "one".,,,,in the preface of against heresies book one irenaeus states,,,,,,,"I refer especially to the disciples of Ptolemaeus"who he also states is of the school of Valentinus,,,,notice irenaeus shows ownership of the changing of "iota and eta" to "potolemaeus",,,,who was of the school of valentinus,,,,,,so whose definition of aeon?,,aeon is Latin(proves the text this is from),,,aieon is greek,,eon,english,,,you knew it.But back to aeons definition,,"whose?",,,,irenaenus directs this "especially" to "Potolemaeus",,,who valentinus taught,,,,,that is potolemaeus is who changed "iota to eta",,,,,,,,,and so out of the fog of the branches it is his "definition of the aeons of the pleroma",,,,,,you are looking for in chapter 1.book 1 he states it in detail.,,,,,,,,,so who changed 666 to 616?,,"ptolemaeus",,,,,,