“There is only one answer to this: the ancients, with a few illustrious exceptions, entirely lacked the capacity to concentrate their interest on the transformations of inanimate matter and to reproduce the natural process artificially, by which means alone they could have gained control of the forces of nature. What they lacked was training in directed thinking.15 The secret of cultural development is the mobility and disposability of psychic energy. Directed thinking, as we know it today, is a more or less modern acquisition which earlier ages lacked.”