Isaiah 29:11

And clearly, if we hear negligently, if we bring no zeal to learning and understanding, not only are the Scriptures of the law and prophets but also of the apostles and Gospels covered for us with a great veil. I fear, however, lest by too much negligence and dullness of heart the divine volumes are not only veiled to us but also sealed, so that "if a book should be put into the hand of a man who cannot read to be read, he would say, 'I cannot read'; if it should be put into the hands of a man who can read, he would say, 'It is sealed.' " Whence it is shown that we must not only employ zeal to learn the sacred literature, but we must also pray to the Lord and entreat "day and night" that the Lamb "of the tribe of Judah" may come and himself taking "the sealed book" may deign to open it. For it is he who "opening the Scriptures" kindles the hearts of the disciples so that they say, "Was not our heart burning within us when he opened to us the Scriptures?"

For our Lord Jesus Christ did not come as it were to seal up the visions of the prophets. He rather opened and explained those that were of old obscure and sealed, tearing away so to say the seals impressed on them, and taught his disciples the meaning of the Holy Scriptures. Hence he says, "Behold, the lion of the tribe of Judah has prevailed, and he has opened the seals that were set on the book," in John's Apocalypse. What are these seals but the obscurities of the prophets? Isaiah knew them well and definitely says too: "And these words shall be as the words of the sealed book." The Christ of God did not come then to shut up the vision and the prophet but rather to open them and bring them to the light.

What is this gate that is always closed, and only the Lord God of Israel enters through it? Namely, the one about which the Savior speaks in the Gospel: Woe to you, scribes and Pharisees, hypocrites! And woe to you, teachers of the law, who take away the key of knowledge! You yourselves do not enter, and you hinder those who are entering. Isaiah also writes about this book under this name: The words of this book shall be like the words of a sealed book: if you give it to a man who cannot read, saying, 'Read this,' he will say, 'I cannot read.' And they shall give the book to a man who knows letters, saying: Read; and he shall say: I cannot read, for it is sealed. But this is the book that no one can unseal or open the seals, neither in heaven, nor on earth, nor under the earth, except for the one of whom it is said in the Apocalypse of John: Behold, the lion of the tribe of Judah, the root and offspring of David, has conquered, so that he may open the book and unseal its seals. For before the Savior assumed a human body and humbled himself, taking on the form of a servant, the Law and the Prophets, and all the knowledge of the Scriptures, were closed, and paradise was closed. But after he hung on the cross, and spoke to the thief, 'Today you will be with me in paradise,' immediately the veil of the temple was torn, and everything was opened; and with the veil removed, we say: But we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image, from glory to glory.

But Thou, O Daniel, shut up the words and seal the book, even to the time appointed. Many shall pass over, and knowledge shall be manifold. He who had revealed manifold truth to Daniel now signifies that the things he has said are matters of secrecy, and he orders him to roll up the scroll containing his words and set a seal upon the book, with the result that many shall read it and inquire as to its fulfilment in history, differing in their opinions because of its great obscurity. And as for the statement, "Many shall pass over" or "go through," this indicates that it will be read by many people. For it is a familiar expression to say: "I have gone through a book," or, "I have passed through an historical account." Indeed this is the idea which Isaiah also expressed in regard to the obscurity of his own book: "And the sayings of that book shall be like the words of a book that is sealed. And if they shall give it to an illiterate man, saying, 'Read it,' he will reply, 'I do not know how to read.' But if they give it to a man who does know how to read and say, 'Read the book,' he will reply, 'I cannot read it, because it is sealed up.'" Also in the Revelation of John, there is a book seen which is sealed with seven seals inside and outside. And when no one proves able to break its seals, John says, "I wept sore; and a voice came to me, saying, 'Weep not: behold the Lion of the tribe of Judah, the Root of David, has prevailed to open the book and break its seals.'" But that book can be opened by one who has learned the mysteries of Scripture and understands its hidden truths, and its words which seem dark because of the greatness of the secrets they contain. He it is who can interpret the parables and transmute the letter which killeth into the spirit which quickeneth.

In the Apocalypse a book is shown sealed with seven seals, which if you deliver to one that is learned saying, "Read this," he will answer you, "I cannot, for it is sealed." How many there are today who fancy themselves learned, yet the Scriptures are a sealed book to them, and one which they cannot open save through him who has the key of David, "he that opens and no man shuts; and shuts and no man opens." In the Acts of the Apostles the holy eunuch when reading Isaiah is asked by Philip, "Do you understand what you are reading?" The man answered, "How can I, except some man should guide me?" To digress for a moment to myself, I am neither holier nor more diligent than this eunuch, who came from Ethiopia … and was so great a lover of the law and of divine knowledge that he read the holy Scriptures even in his chariot. Yet although he had the book in his hand and took into his mind the words of the Lord, no, even had them on his tongue and uttered them with his lips, he still did not know him, who—not knowing—he worshiped in the book. Then Philip came and showed him Jesus, who was concealed beneath the letter. Wondrous excellence of the teacher! In the same hour the eunuch believed and was baptized; he became one of the faithful and a saint. He was no longer a pupil but a master; and he found more in the church's font there in the wilderness than he had ever done in the gilded temple of the synagogue. These instances have been just touched upon by me (the limits of a letter forbid a more discursive treatment of them) to convince you that in the Holy Scriptures you can make no progress unless you have a guide to show you the way.