Many books require no thought from those who read them, and for a very simple reason; they made no such demand upon those who wrote them. Those works, therefore, are the most valuable that set our thinking faculties in the fullest operation. For as the solar light calls forth all the latent powers and dormant principles of vegetation contained in the kernel, but which, without such a stimulus, would neither have struck root downward, nor borne fruit upward, so it is with the light that is intellectual, it calls forth and awakens into energy those latent principles of thought in the minds of others, which without this stimulus reflection would not have matured, nor examination improved, nor action embodied.
Also attributed to: Colton
The point
The best books demand thought from readers because they demanded thought from their writers.