The famous saying “Ignorance of the Scriptures is ignorance of Christ” is attributed to St. Jerome, and is said to be found in his preface on Isaiah. I’ve found only one version of said preface online at CCEL, reproduced here:
No one, when he will have seen the Prophets to be written in verses, would think them to be bound in meter among the Hebrews, and to have anything in common with the Psalms or the works of Solomon. But what is customary to be used in Demosthenes and Cicero, as they are written in words with divisions, who certainly wrote prose and not in verses, we also, providing ease of reading, have divided a new translation with a new kind of writing. And first, knowing of Isaiah what is presented in his speech, certainly as a man noble and of urbane elegance he does not have anything of rusticity mixed into (his) speech. For this reason it happens that in comparison with others the translation was not able to preserve the flower of his speech. And then adding this, that it is being spoken not only by a prophet, but by an evangelist. For thus all the mysteries of Christ and the Church are pursued to clarity, so that you would not think them to be prophesied of the future, but they covered the history of things past. For this reason I suppose the Seventy interpreters to have been unwilling at that that time to set forth clearly for the gentiles the sacraments of their faith, not throwing holy things to dogs or pearls to swine, which things, when you will have read this edition, you will note were hidden by them.
Nor am I unaware of how much work it is to understand the Prophets, or for anyone not to be easily able to judge from the translation, unless he will have before understood those things which he will have read, and we to suffer from the bites of many, who, being goaded by jealousy, what they are not able to follow, they despise. Therefore, knowing and being wise, I place my hand in the fire, and nevertheless I pray this for the scornful readers: that just as the Greeks after the Seventy translators read Aquila and Symmachus and Theodotion, either for study of their doctrines or so that they better understand the Seventy through their collation, that these are deemed worthy to have at least one translator after the earlier ones. Reading first and afterward despising, they are seen not to condemn by judgment, but rather by the ignorant presumption of hatred.
And Isaiah prophesied in Jerusalem and Judea when the ten tribes had not yet been led into captivity, and the oracle covered both kingdoms, now together, now separately. And while he sometimes looks at present history, and indicated the return of the people to Judea after the Babylonian captivity, yet is all his concern for the calling of the nations and for the coming of Christ. Who, how much the more you love, O Paula and Eustochium, the more strive for him, so that for the present disparagement, by which the envious incessantly tear me into pieces, the same One may restore a reward to me in the future, Who knows me to have exerted myself in the learning of foreign languages: the Jews might not jump all day on the errors of the Scriptures in His Church.
I can’t find anything that could be construed as the oft-quoted phrase.
Is there a copy – even in Latin! – of his complete preface to Isaiah online somewhere I could look at?