"That law of nature whereby everything climbs to higher platforms, and bodily vigor becomes mental and moral vigor. The bread he eats is first strength and animal spirits; it becomes, in higher laboratories, imagery and thought; and in still higher results, courage and endurance. This is the right compound interest; this is capital doubled, quadrupled, centupled; man raised to his highest power. The true thrift is always to spend on the higher plane; to invest and invest, with keener avarice, that he may spend in spiritual creation and not in augmenting animal existence."