4 But thou, O Daniel, shut up the words, and seal the book, even to the time of the end: many shall run to and fro, and knowledge shall be increased.

This book is going to be a book of mystery, Daniel, because noone is going to understand it until ‘the time of the end’. But men of every generation are going to turn back and forth in its pages because they think they are the last generation and want to prove it by expressing that all the prophecies of Daniel have been fulfilled.
The mystery will not be even guessed at properly until all the players are in place and that will be; and here is the key; 'even to the time of the end'. When all the players are in place, then will the knowledge be available to open the book.