I believe that pure thinking will do more to educate a man than any other activity he can engage in. To afford sympathetic entertainment to abstract ideas, to let one idea beget another, and that another, till the mind teems with them; to compare one idea with others, to weigh, to consider, evaluate, approve, respect, correct, refine; to join thought with thought like an architect till a whole edifice has been created within the mind; to travel back in imagination to the beginning of the creation and then to leap swiftly forward to the end of time; to bound upward through illimitable space and downward into the nucleus of an atom; and all this without so much as moving from our chair or opening the eyes – this is to soar above all the lower creation and come near to the angels of God.