Grrrr... I had typed an entire section and then my browser locked up... so Im typing this again...
Irenaeus would have been familiar with the Jewish use of numbers as symbols. Not to predict the future but rather because numbers represented something. Even today, we might say that 13 is an unlucky number because there were 13 people (that we know of) at the Last Supper.
Years ago, I had a Bible study (Lutheran) that we studied Revelation and got a basic introduction into the numbers in Rev. This is what I remember, so forgive me if Im off on some things...
One - represents divinity - The Lord thy God is one.
two - represents the Jewish law, as in the 2 tablets of the Law that Moses brought down. (Laughing as I think of Mel Brooks in History of the World Part 1... "I have here 15, <crash> 10, 10 commandments)
Three- a complete number. Of course for us, the Trinity, but for Jews this would have represented a spiritual completeness, of body, mind and soul
Four - a complete number. Represents the earthly completeness, the four directions, the four elements, and in Irenaeus case, 4 Gospels
Five - represents man - five fingers on a hand
Six - an incomplete number, falling short of the great complete number, seven. 666 can be taken to mean a being who tries to counterfit God, and falls short by one, three times.
Seven - THE complete number. 3+4 meaning spiritual and earthly completeness. In the wisdom literature like Proverbs, you'll see, 6 times you do this, 7 times you do this. In this case, Proverbs is giving a "complete" list. In Christianity we have the 7 deadly sins, and the 7 heavenly virtues
Eight - Dont think this one had a meaning
Nine - 3x3, so spiritual completeness by spiritual completeness. Paul says there are nine sets of spiritual beings: thrones, principalities, angels, archangels etc.
Ten - Another complete number, ten commandments, ten fingers, ten toes, also representing man.
12 - represents Israel, with the 12 tribes of Israel.
1000 - 10 x 10 x 10 - Ten in its completeness
144,000 - Israel in its completeness 12 x 12 x 1000
Jesus uses these numbers when Peter asks how many times should I forgive someone. Not just seven times, but 7 times 70. So here the disciples would have understood that this doesnt mean once you forgive someone 490 times and at 491 you can tell him to shove off. Rather, they would have taken it to me ALWAYS forgiving, 7 x 7 x 10 as forgive as God forgives.
Brian