Mrs. Bagley took a sandwich and a glass of milk to James and found him sitting on a chair, a heavy headset covering most of his skull, reading aloud from a textbook on electronic theory. Mrs. Bagley stopped at the door, unaccountably startled. James looked up and shut off his work. "It's finished," he said with grave pride. "All of it?" "Well," he said, pondering, "the basic part. It works." Mrs. Bagley looked at the scramble of equipment in the room as though it were an enemy. It didn't look finished. It didn't even look safe. But she trusted James, although she felt at that moment that she would grow old and die before she understood why and how any collection of apparatus could be functional and still be so untidy. "It--could teach me?" "If you had something you want to memorize." "I'd like to memorize some of the pet recipes from my cookbook." "Get it," directed James. She hesitated. "How does it work?" she wanted to know first. He countered with another question. "How do we memorize anything?" She thought. "Why, by repeating and repeating and rehearsing and rehearsing." "Yes," said James. "So this device does the repetition for you. Electromechanically." "But how?" James smiled wistfully. "I can give you only a thumbnail sketch," he said, "until I have had time to study the subjects that lead up to the final theory." "Goodness," exclaimed Mrs. Bagley, "all I want is a brief idea. I wouldn't understand the principles at all." "Well, then, my mother, as a cerebral surgeon, knew the anatomy of the human brain. My father, as an instrument-maker, designed and built encephalographs. Together, they discovered that if the great waves of the brain were filtered down and the extremely minute waves that ride on top of them were amplified, the pattern of these superfine waves went through convolutions peculiar to certain thoughts. Continued research refined their discovery. "Now, the general theory is that the cells of the brain act sort of like a binary digital computer, with certain banks of cells operating to store sufficient bits of information to furnish a complete memory. In the process of memorization, individual cells become activated and linked by the constant repetition. "Second, the brain within the skull is a prisoner, connected to the 'outside' by the five standard sensory channels of sight, sound, touch, taste, and smell. Stimulate a channel, and the result is a certain wave-shape of electrical impulse that enters the brain and--sort of like the key to a Yale lock--fits only one combination of cells. Or if no previous memory is there, it starts its own new collection of cells to linking and combining. When we repeat and repeat, we are deepening the groove, so to speak.