intimate relation between the evolutional stages of society and the evolutional stages of science. It is this therefore that accounts for the tremendous importance of the evolution of the sciences through the three stages, the theological, the metaphysical and the positive. In his chief work, Cours de philosophie positive (1830–42), Comte develops the law of the three stages by furnishing both a clarification of the sciences and an encyclopedic exposition of the positive knowledge of his age.
At the theological stage human knowledge governs but a very small portion of experience, and hence the imagination plays an important part. The bond which at this stage unites the facts for the human mind is the idea of gods and spirits. The only way of explaining the events which transpire in the universe is by reference to these ideas, and the importance of theology in the history of civilization rests upon the fact that it was the intellectual bond upon this primitive stage of science. It was likewise of practical importance, because morality was essentially founded on religious authority. Within the theological stage the transition from fetichism to polytheism is especially significant because, by the removal of divine beings from the particular phenomena of nature, it became possible to subject these phenomena to an empirical investigation.
At the metaphysical stage the explanation of natural phenomena is no longer found to consist of personal beings, but in universal energies or ideas. There are just as many distinct energies postulated as the number of distinct groups of phenomena require; thus we speak of a chemical energy, a vital energy, etc., and finally we postulate the idea of nature (an abstract equivalent of the idea of God) for the total aggregate of phenomena.
