But why give them a sort of prerogative? Why choose them in preference to all others as the subject of our study?--It is merely for reasons of method.
In the first place, we cannot arrive at an understanding of the most recent religions except by following the manner in which they have been progressively composed in history. In fact, historical analysis is the only means of explanation which it is possible to apply to them. It alone enables us to resolve an institution into its constituent elements, for it shows them to us as they are born in time, one after another. On the other hand, by placing every one of them in the condition where it was born, it puts into our hands the only means we have of determining the causes which gave rise to it. Every time that we undertake to explain something human, taken at a given moment in history--be it a religious belief, a moral precept, a legal principle, an æsthetic style or an economic system--it is necessary to commence by going back to its most primitive and simple form, to try to account for the characteristics by which it was marked at that time, and then to show how it developed and became complicated little by little, and how it became that which it is at the moment in question. One readily understands the importance which the determination of the point of departure has for this series of progressive explanations, for all the others are attached to it. It was one of Descartes's principles that the first ring has a predominating place in the chain of scientific truths. But there is no question of placing at the foundation of the science of religions an idea elaborated after the cartesian manner, that is to say, a logical concept, a pure possibility, constructed simply by force of thought. What we must find is a concrete reality, and historical and ethnological observation alone can reveal that to us. But even if this cardinal conception is obtained by a different process than that of Descartes, it remains true that it is destined to have a considerable influence on the whole series of propositions which the science establishes. Biological evolution has been conceived quite differently ever since it has been known that monocellular beings do exist. In the same way, the arrangement of religious facts is explained quite differently, according as we put naturism, animism or some other religious form at the beginning of the evolution. Even the most specialized scholars, if they are unwilling to confine themselves to a task of pure erudition, and if they desire to interpret the facts which they analyse, are obliged to choose one of these hypotheses, and make it their starting-point. Whether they desire it or not, the questions which they raise necessarily take the following form: how has naturism or animism been led to take this particular form, here or there, or to enrich itself or impoverish itself in such and such a fashion? Since it is impossible to avoid taking sides on this initial problem, and since the solution given is destined to affect the whole science, it must be attacked at the outset: that is what we propose to do.