The sin of reason...Father Ruiz-Sanchez was a dedicated man--a priest who was also a scientist, and a scientist who was also a human being. He found no insoluble conflicts in his beliefs or his ethics until he was sent to Lithia. There he came upon a race of aliens--reptilian in form--who were admirable in every way except for their total reliance on cold reason; they were incapable of faith and belief.On Lithia, Father Ruiz-Sanchez also found a scientific riddle, and he was presented with an ethical problem that reached across two worlds!Father Ruiz-Sanchez was then torn in a struggle between the teachings of his faith, the teachings of his science, and the inner promptings of his humanity., There was only one solution. He had to accept an ancient and unforgivable heresy--and in accepting that heresy, he risked the futures of both worlds!HUGO AWARD WINNER!