I, Robot

by Isaac Asimov

She went on, “So he accepted the item, but not without a certain jar. Even with death temporary and its importance depressed, it was enough to unbalance him very gently.” She brought it out calmly, “He developed a sense of humor—it’s an escape, you see, a method of partial escape from reality. He became a practical joker.” Powell and Donovan were on their feet. “What?” cried Powell. Donovan was considerably more colorful about it. “It’s so,” said Calvin. “He took care of you, and kept you safe, but you couldn’t handle any controls, because they weren’t for you—just for the humorous Brain. We could reach you by radio, but you couldn’t answer. You had plenty of food, but all of it beans and milk. Then you died, so to speak, and were reborn, but the period of your death was made . . . well . . . interesting. I wish I knew how he did it. It was The Brain’s prize joke, but he meant no harm.”