Everything is in Destiny's book, at least that is the theory. Delirium has said that there are things that are not in Destiny's book, paths outside of his garden, so perhaps he does not know everything. But is the knowledge contained within Destiny himself, or is it contained in his book? It has been suggested that the book contains the knowledge, so Destiny himself does not have to bear the burden of knowing everything, and that he learns by turning the page as we learn by experience. He can be suprised, and his book records his reactions even before they occur. His book is chained to him, to prevent it being taken from him (although it has been rumored that pages have been stolen, even though the book itself recorded these events before they happened so Destiny knew it would happen), and to prevent him being able to free himself from the book, and the burden of the future. The oldest of the Endless holds a great burden, as they all do, in their own ways. Destiny's burden may be lightened by his book, which contains the knowledge so he does not have to. Of all the Endless he may be the most tied to his duty, both physically and figuratively, aside possibly from his younger brother Dream. But Destiny's burden does not require the imagination Dream's does, which may be why it was Dream, not Destiny, who had to make way for a new incarnation.