"Well," Diana said, "as long as the weights stay in place, the wheel spins evenly. But if you remove one of the weights, the wheel's out of balance. It starts to wobble." Forrester took one of the weights (Dionysus, a rather large, jolly weight) off the wheel in his mind. It wobbled. "Right," he said. "It can take the wobble for a little while. But unless the balance is restored in time, the wheel will eventually break." Hurriedly, Forrester put Dionysus back on the wheel. The wobble stopped. "Oh," he said. "I see." "Our power machine works in that sort of way. That is, it requires all fifteen occupants. Dionysus has been dead for three years now, and that's about the outside limit. Unless he's replaced soon, the machine will be ruined." Forrester opened his eyes. The wheel spun away and disappeared. "So you found me to replace Dionysus. I had to look like him, so the mortals wouldn't see any difference. And the psychological similarity--" "That's right," Diana said. "It's the same as the wheel again. If you remove a weight, you've got to put back a weight of the same magnitude. Otherwise, the wheel's still out of balance." "And since the power machine works through the nervous system--" "The governing factor is that similarity. You've got to be of the same magnitude as Dionysus. Of course, you don't have to be an _identical_ copy. The machine can be adjusted for _slight_ differences." "I see," Forrester said. "And the fifteen power nodes--" Another idea occurred to him. "Wait a minute. If there are only fifteen power nodes, then how come there were so many different Gods and Goddesses among the Greeks? There were a lot more than fifteen back then." "Of course there were," Diana said, "but they weren't real Gods. As a matter of fact, some of them didn't really exist." Forrester frowned. "How's that again?" "They were just disguises for one of the regular fifteen. Aesculapius, for instance, the old God of medicine, was Hermes/Mercury in disguise--he took the name in honor of a physician of the time. He would have raised the man to demi-Godhood, but Aesculapius died unexpectedly, and we thought taking his 'spirit' into the Pantheon was good public relations." "How about the others?" Forrester said. "They weren't all disguises, were they?" "Of course not. Some of them were demi-Gods, just like yourself. Their power was derived, like yours, from the Pantheon instead of directly through the machine. And then there were the satyrs and centaurs, and suchlike beings. That was public relations, too--mainly Zeus' idea, I understand. The original Zeus, of course." "Of course," Forrester said. "The satyrs and such were artificial life-forms, created, maintained and controlled by the machine itself. It's equipped with what you might call a cybernetic brain--although that's pretty inadequate as a description. Vulcan could do a better job of explaining." "Perfectly all right. I don't understand that kind of thing anyhow."