A further danger attends the student of religions. This arises from prepossession rather than from hypothesis and leads him to mistake deduction for induction. He finds, we will suppose, what he takes to be a latchkey. It is an instrument considerably the worse for wear and of a somewhat unusual pattern. He is quite certain it is a key. There is no room for doubt. He determines to find a lock which it will fit. Starting with the key he examines locks prehistoric, mediæval and modern, but all in vain, for the simple reason that the implement in his hands is not a key at all but the head of a fish spear. It is not the critical method of induction but the uncritical method of deduction which is to be reprobated. When, for example, we discover by observation, the practical universality of sacrifice as a distinguishing mark of religion, we may explain the fact in a dozen different ways, but in every case we are compelled to recognise the belief in a God of some sort, and when we find that generally, at some stage of religious development, sacrifice is offered by way of propitiation, we are led to the conclusion that safety and salvation were held to be only possible by atonement. We have before us a multitude of locks and one key fits them all, and we are therefore led to conclude that _au fond_ offence and sacrifice are related as poison to antidote. When, however, we descend to particulars, resemblances and coincidences are found to be as misleading as the salvationist’s tunic. Their evidential value, to use a threadbare but useful phrase, is infinitesimally small and sometimes a negative quantity. Relying upon resemblance, a person might be led to conclude that it was the spring turnip which suggested the shape of the watch and the duck’s egg the morphology of toilet soaps. Utility and convenience have entered largely into the ritual systems of all religions. The same accessories are required for the worship of Baal as for the worship of Jehovah. To identify Baal with Jehovah is to beg the question and to fall a victim to the tyranny of coincidence and resemblance.