What really remains for discussion is a problem of socio-psychology. That is, we have to determine the conditions of origin of so widespread a belief, but which we believe to be false. The materials for answering this question are now at our command, and whatever differences of opinion there may be concerning the stages of development, there is very little concerning their essential character. And it is not without significance that this question of origin is one that the present-day apologists of theism seem pretty unanimous in leaving severely alone. Let us commence with the fact that religion is something that is acquired. Every work on the origin of religion assumes it, and all investigation warrants the assumption. The question at issue is the mode of acquisition. And here one word of caution is advisable. The wide range of religious ideas and their existence at a very low culture stage, precludes the assumption that religious ideas are generated in the same conscious way as are scientific theories. Even with the modern mind our conclusions concerning many of the affairs of life are formed in a semi-conscious manner. Most frequently they are generated subconsciously, and are only consciously formulated under pressure of circumstances. And if we are to understand religion aright we must be on our guard against attributing to primitive mankind a degree of scientific curiosity and reflective power to which it can lay no claim. We have to allow for what one writer well calls "physiological thought," thought, that is, which rises subconsciously and has its origin in the pressure of insistent experience. A comprehensive survey of religious beliefs show that there are only two things that can be said to be common to them all. They differ in teachings, in their conceptions of deity, and in modes of worship. But all religions agree in believing in some kind of ghostly existence and in a continued life beyond the grave. I use the expression, "ghostly existence," because we can really trace the idea of God backward until we lose the definite figure in a very general conception, much as astronomers have taught us to lose a definite world in the primitive fire-mist. So when we get beyond the culture stage at which we meet with the definite man-like God, we encounter an indefinite thought stage at which we can dimly mark the existence of a frame of mind that was to give birth to the more concrete conception. The most general term for the belief in the various orders of gods thus becomes the belief in invisible, super-material beings, like, and yet superior to man. It is for this reason that Professor Tylor's definition of religion as "the belief in spiritual beings--so long as we do not use the term "spiritual" in its modern sense"--seems to me the moat satisfactory definition yet offered. It is the one point on which all religions agree, and for this reason may be regarded as their essential feature.