I had scarcely entered the room when I saw on my table an open book I had not put there. It was the works of Cardano. I did not intend to read it, but my gaze fell as though compelled on a story told by that philosopher. He writes that he was studying one night by candlelight when he saw two tall old men come in through the closed doors of his room. He asked them many questions, and they finally told him they were from the Moon; whereupon they disappeared. I was so surprised, both by the book that had put itself on my table and by the page it was open to, that I took this chain of events for an inspiration from God, who was urging me to tell people that the Moon is a world.