From another point of view the following pages may be regarded as an attempt more completely to apply scientific principles to religious beliefs. And it would be idle to hope that such an attempt could be made without incurring much hostile criticism. In connection with most other subjects the help of science is welcomed; in connection with religion science is still regarded as more or less of an intruder, profaning a sacred subject with vulgar tests and impertinent enquiries. This must almost inevitably follow when one has to face the opposition of thousands of men who have been trained to regard themselves as the authorised exponents of all that pertains to religion, but whose training fails to supply them with a genuine scientific equipment. It should, however, be clear that an attitude of hostility to science, veiled or open, cannot be maintained. Mere authority has fallen on evil days, and in all directions is being freely challenged. There is increasing dislike to systems of thought that shrink from examination, and to conclusions that cannot withstand the most rigorous investigation. And if science really has anything of value to say on this question it cannot be held to silence for ever. Sooner or later the need for its assistance will be felt, and the self-elected authority of an order must give way. It is, moreover, impossible for science with its claim, sometimes avowed, but always implied, to cover the whole of life, to forego so large a territory as that of religion. For there can be no reasonable question that religion has played, and still plays a large part in the life of the race. Whatever be the nature of religion, science is bound either to deal with it or confess its main task to be hopeless. Whether or not it is possible to apply known scientific principles to the whole of religion will be a matter of opinion; but the attempt is at least worth making. So much that appeared to be beyond the reach of science has been ultimately brought within its ken, so many things that seemed to stand in a class by themselves have been finally brought under some more comprehensive generalisation, and so become part of the 'cosmic machine,' that one is impelled to believe that given time and industry the same will result here. And it should never be forgotten that one aspect of scientific progress has been the taking over of large tracts of territory that religion once regarded as peculiarly its own; and just as psychology and pathology were found to hold the key to an understanding of such a phenomenon as witchcraft, so we may yet realise that a true explanation of religious phenomena is to be found, not in some supernatural world, but in the workings of natural forces imperfectly understood.