Now we say, the law itself is the key of knowledge. For it was both a shadow and a figure of the righteousness of Christ, therefore it became the Lawyers, as instructors of the Law of Moses and the words of the Prophets, to reveal in a certain measure to the Jewish people the knowledge of Christ. This they did not, but on the contrary detracted from the divine miracles, and spoke against His teaching, Why hear ye him? So then they took away the key of knowledge. Hence it follows, Ye entered not in yourselves, and them that were entered in ye hindered. But faith also is the key of knowledge. For by faith comes also the knowledge of truth, according to that of Isaiah, Unless ye have believed, ye will not understand. (Isa. 7:9. LXX.) The Lawyers then have taken away the key of knowledge, not permitting men to believe in Christ.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).