"Does it tell how the planets rule men's fates?" Daoud asked. "That is a ridiculous, irrational, and superstitious notion." Fra Tomasso waved the suggestion away with a stubby-fingered hand. Daoud felt a cold wave of terror. Had he said something that gave him away? But Fra Tomasso, leaning back in his squeaking chair, seemed unperturbed. And Daoud remembered that Ugolini studied the influence of the stars on human lives. So it could not be such an un-Christian belief. The Dominican pointed over his shoulder to the window of his cell, a large rectangle cut in the curving whitewashed wall. This was one of the few rooms Daoud had entered in Italy that was not covered with idolatrous or obscene paintings, and he liked its austerity. Except, of course, for the ubiquitous figure of Jesus the Messiah, crucified, hanging opposite the window. Daoud tried to avoid looking at the crucifixes because they reminded him of his childhood, but they were everywhere in Orvieto. "Aristotle reasoned about the relations of the heavenly bodies to one another," Fra Tomasso said. "One account of the _De Caelestiis_ declares that he believed that the sun does not move." "But we see it move," Daoud said, surprised. "We think we see it move." D'Aquino smiled. "But have you ever stood on the deck of a galley as it was pulling away from the quay and had the feeling that the quay was moving while the ship was standing still? Well then, what if the earth is moving, just like a ship on whose deck we stand, while the sun remains fixed?" Daoud thought about the vast and solid earth and the daily journey of the sun like a bright lamp across the sky. It was self-evident which one of them moved. But he sensed that Fra Tomasso was in love with this idea. He had best not argue too strenuously against it. "Ingenious," he said. _Ridiculous_, he thought to himself. _This man dismisses astrology and approves greater absurdities._ "I myself suspected that the sun might be stationary while the earth moves long before I learned that Aristotle might also believe so." Fra Tomasso waved a hand toward the window again. His cell was the top floor of one of the towers fortifying the Dominican chapter house, an anthill of constant, mysterious activity. D'Aquino's window overlooked the north side of Orvieto's wall. There was no covering on the window, and the shutters were open to let in the cool mountain air. Daoud gazed upon the rolling hills, bright green in the sunlight, beyond Orvieto's battlements. This was a lovely country, he thought. Back in Egypt the hills would be brown this time of year. "Look how much light and heat we get from the sun," Fra Tomasso went on. "Yet, the sun appears small--I can hide it with my thumb." _Your thumb could hide four or five suns._ "Perhaps it _is_ small," Daoud said.