Irenaeus on Prophecy

I came across Irenaeus' description of prophecy and thought it worthy of sharing in light of the advent season and the readings of infancy narratives, particularly Matthew's, full of "fulfilled" scripture:

"If any one, therefore, reads the Scriptures with attention, he will find in them an account of Christ, and a foreshadowing of the new calling [. . .]. His human nature could not be understood, prior to the consummation of those things which had been predicted, that is, the advent of Christ. [. . .] For every prophecy, before its fulfilment, is to men [full of] enigmas and ambiguities. But when the time has arrived, and the prediction has come to pass, then the prophecies have a clear and certain exposition." (Against Heresies, 4.26.1; Translation ANF 1.496).