"This learned scholar held that the power of man's will was such that, under certain circumstances, it could be so far impressed upon those diffused forces of life about us as to materialize or concentrate them, and so render them cognizant to the human understanding, or, in other words, visible. Now, Oliver, it is very well known that one man may so impress his will upon another as to render that other will entirely subservient to his own. Under such conditions, the one so impressed sees, feels, smells, tastes, and senses only as the superior will orders; he moves, speaks, and exists as the other commands. If that power, Yusef Ben Djani argued, could impress material men in this world, why could it not impress men in the world immediately beyond? Is not a man, he reasoned, the same man after quitting this world as when he lived in the body? Why, then, is he not as subject to that psychological power there as here, and why, then, could he not be influenced there as well as here? Such an influence Yusef Ben Djani did exert, and succeeded. He materialized those quiescent forces of life, and brought them into such communion with himself that he was able to compel them to that certain exudation of life in quiescence which we in this world call matter. Do you understand me, Oliver?" Oliver shook his head. "No," said he, "I do not." He had tried to follow the other so far as he was able, but he had long gotten beyond the power of comprehension; the words fell upon his ears one after the other like blows, until his head hummed like a beehive. The other laughed. "Very well," said he. "It is of no importance that you should comprehend Yusef Ben Djani's theory. But this at least you can understand: he materialized evil spirits. "Now there was a certain young Venetian student named Nicholas Jovus, who almost from his childhood had possessed a wonderful psychological power upon others. By psychological power I mean the power of superinducing his own will upon the will of another; in other words, to make such another do absolutely as he chose.