In this book we propose to study the most primitive and simple religion which is actually known to make an analysis of it and to attempt an explanation of it. A religious system may be said to be the most primitive which we can observe when it fulfils the two following conditions: in the first place when it is found in a society whose organization is surpassed by no others in simplicity;[1] and secondly when it is possible to explain it without making use of any element borrowed from a previous religion.