What did the Romans know about their gods? Why did they perform the rituals of their religion, and what motivated them to change those rituals? To these questions Clifford Ando proposes simple answers: that in contrast to ancient Christians, who had faith, Romans had knowledge, and their knowledge was empirical in orientation. In other words, the Romans acquired knowledge of the gods through observation of the world, and their rituals were maintained or modified in light of what they learned. After a preface and opening chapter that lay out this argument about knowledge and place it in context, Ando pursues a member of themes. In particular, he asks whether the Romans could ever have offered a religion to the empire, when their practice involved the transfer of select gods and cults to Rome. He seeks likewise to understand what status the Romans granted their religious institutions, which were understood to be the products of a fallible and never-ending striving for cognitia deorum, knowledge of the gods.