If anyone, therefore, reads the Scriptures [i.e., the Old Testament] this way, he will find in them the Word concerning Christ, and a foreshadowing of the new calling. For Christ is the “treasure which was hid in the field” (Mt 13:44), that is, in this world – for "the field is the world" (Mt 13:38) – [a treasure] hidden in the Scriptures, for He was indicated by means of types and parables, which could not be understood by men prior to the consummation of those things which had been predicted, that is, the advent of the Lord. And therefore it was said to Daniel the Prophet, “Shut up the words, and seal the book, until the time of the consummation, until many learn and knowledge abounds. For, when the dispensation shall be accomplished, they shall know all these things” (Dan 12:4,7). And Jeremiah also says, “In the last days they shall understand these things” (Jer 23:20). For every prophecy, before its fulfillment, is nothing but an enigma and ambiguity to men; but when the time has arrived, and the prediction has come to pass, then it has an exact exposition [exegesis]. And for this reason, when at this present time the Law is read by the Jews, it is like a myth, for they do not possess the explanation [exegesis] of all things which pertain to the human advent of the Son of God; but when it is read by Christians, it is a treasure, hid in a field, but brought to light by the Cross of Christ, and explained, both enriching the understanding of men, and showing forth the wisdom of God, and making known His dispensations with regard to man, and prefiguring the Kingdom of Christ, and preaching in anticipation the good news of the inheritance of the holy Jerusalem, and proclaiming beforehand that the man who loves God shall advance so far as even to see God, and hear His Word, and be glorified, from hearing His speech, to such an extent, that others will not be able to behold his glorious countenance (cf. 2 Cor 3:7), as was said by Daniel, “Those who understand shall shine as the brightness of the firmament, and many of the righteous as the stars for ever and ever” (Dan 12:3). In this manner, then, I have shown it to be, if anyone read the Scriptures. (AH 4.26.1)The cause of every heresy, according to St Irenaeus, is the misinterpretation of Scripture. Speaking of the Gnostics, he writes:
Such is their system that neither the prophets preached, nor the Lord taught, nor the apostles handed down. They boast rather loudly of knowing more about it than others do, citing it from non-scriptural (unwritten) [works]; and as people would say, they attempt to braid ropes of sand. They try to adapt to their own sayings in a manner worthy of credence, either the Lord’s parables or the prophets’ sayings, or the apostles’ words, so that their fabrication might not appear to be without witness. They disregard the order and the connection of the Scriptures and, as much as in them lies, they disjoint the members of the Truth. They transfer passages and rearrange them; and, making one thing out of another, they deceive many by the badly composed phantasy of the Lord’s words that they adapt. By way of illustration, suppose someone would take the beautiful image of a king, carefully made out of precious stones by a skillful artist, and would destroy the features of the man on it and change it around and rearrange the jewels, and make the form of a dog or of a fox out of them, and that rather a bad piece of work. Suppose he would then say with determination that this is the beautiful image of the king that the skillful artist had made, and at the same time pointing to the jewels which had been beautifully fitted together by the first artist into the image of the king, but which had been badly changed by the second into the form of a dog. And suppose he would through this fanciful arrangement of the jewels deceive the inexperienced who had no idea what the king’s picture looked like, and would persuade them that this base picture of a fox is that beautiful image of the king. In the same way these people patch together old women’s fables, and then pluck words and sayings and parables from here and there and wish to adapt these words of God to their fables. (AH 1.8.1)St Irenaeus of Lyon's major work, Against the Heresies, can be found here.