This is not “theology.” That branch of learning aims to measure the objective reality, the concrete truth, of some one or another opinion concerning God and divine things; while the scientific study of religions confines itself exclusively to examining such opinions as phases of human mental activity, and ascertaining what influence they have exerted on the development of the species or of some branch of it. Therefore it is never “polemic.” It neither attacks nor defends the beliefs which it studies. It confines itself to examining their character and influence by the lights of reason and history. The methods which we employ in this process of reduction are three in number: 1. The Historic Method; 2. The Comparative Method; 3. The Psychologic Method. A few words will explain the scope of each of these. The Historic Method studies the history of beliefs and the development of worship. It seeks to discover what influences have been exerted on them by environment, transmission, heredity, and conquest, and to bring into full relief what is peculiar to the tribe or group under consideration, and what is exotic. For in one sense it is true that every nation and tribe, even every man, has his own religion. Such ethnic traits merit the closest scrutiny. They are so marked and constant as to modify profoundly the history of even the ripest religions. It is quite true, as has been observed by an historian of Christianity, that “there is in every people an hereditary disposition to some particular heresy,”[2] that is, to altering any religion which they accept in accordance with the special constitution of their own minds. The Comparative Method notes the similarities and differences between the religions of different tribes or groups, and, gradually extending its field to embrace the whole species, endeavors, by excluding what is local or temporal, to define those forms of religious thought and expression which are common to humanity at large. The Psychologic Method takes the results of both the previous methods and aims to explain them by referring the local manifestations to the special mental traits of the tribe or group, and the universal features to equally universal characteristics of the human mind. The last, the Psychologic Method, is the crown and completion of the quest; for every advanced student of religion will subscribe to the declaration of Professor Granger, that “all mythology and all history of beliefs must finally turn to psychology for their satisfactory elucidation.”[3] In other words, the laws of human thought can alone explain its own products.