"Ancient [Graeco-Roman] religion was tolerant and non-sectarian. In this it was unlike ancient philosophy. The adherents of Epicurean and Stoic philosophy fought long and acrimonious feuds, as one can see by reading Lucretius. The reason for this difference between religion and philosophy is that philosophers maintained various factual propositions about the world—that it was made of 'breath' or atoms, that it was finite or infinite, and so on—whereas ancient religions only presupposed the existence of forces capable of being persuaded by prayer and sacrifice. Since Roman religion offered no dogmas about the universe, there was nothing for people to contradict or to argue about. Philosophers, on the other hand, had elaborate systems which they defended to the last detail with grotesque ingenuity."