Daniel 9:2

in the first year of his reign I, Daniel, understood by books, he observed, he got his information, and then drew his conclusions, the number of the years whereof the word of the Lord came to Jeremiah, the prophet, Cf Jeremiah 25:11, that he would accomplish seventy years in the desolations of Jerusalem, or, "that seventy years would be completed in the desolate condition of Jerusalem. " Note that Daniel was in possession of a book of Jeremiah's prophecies, which, therefore, must have been in existence in a number of copies even then, that he considered the words of this book as the Word of Jehovah, and that he definitely believed the words of the prophecy, as the words of the Lord, would be fulfilled.