From very early times human beings must have been aware of cycles of events and would have had expectations based on past experiences. But they would also have appreciated that often their expectations were not fulfilled. Hence beliefs in orderly sequences in the world about them were modified by beliefs that the course of nature was subject to the wishes and decrees of capricious and possibly malevolent spirits, so that explanations of the unusual or the unexpected presupposed their intervention. But though the spirits were thought to have superhuman powers they were credited with human appetites and emotions and therefore they might be influenced by entreaty and by flattery: with suitable propitiation ceremonies mankind might hope to have some control, albeit indirect control, over events. Thus early ideas about the world and primitive attempts to influence the course of nature were intimately involved with religion and with religious rites. Even the much more sophisticated theories and practices of Ancient Egypt, Babylon, India, China and Ancient Greece and Ancient Rome were profoundly influenced by religion, and in all countries ultimate explanations of events were in terms of the desires and purposes of the gods.