5 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 (or rather “man” for so the scripture calls him) when reading Isaiah he is asked by Philip “Do you understand what you read?”, makes answer:— “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, that is from the ends of the world, to the Temple leaving behind him a queen's palace, 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, nay even had them on his tongue and uttered them with his lips, he still knew not Him, whom— not knowing— he worshipped 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.
Source: Letters (New Advent)