"1. Those which require the addition to ordinary matter of an immaterial or spiritual essence, substance, or power, general or local, whose presence is the efficient cause of life; and, "2. Those which attribute the phenomena of life solely to the mode of combination of the ordinary material elements of which the organism is composed, without the addition of any such immaterial essence, power, or force." It is quite true that physiologists have up to this time argued out these two alternatives, and that at present the second is probably the more prevalent. It is however also true that neither includes or can possibly include the whole truth, and that enlightened theism may enable us to hold both, or all that is true in either. Undoubtedly we must hold that a higher spiritual power or Creator is necessary to the existence of life; but then this is necessary also to the existence of dead matter and force. So that if physiologists think proper to trace the whole phenomena of life to material causes, they do not on that account in any way invalidate the evidence for a spiritual Creator, nor for a spiritual element in the higher nature of man. Yet so inconceivably shallow is much of the biological reasoning of the day, that it is quite common to find physiologists referring all life to spontaneous and uncaused material agencies, because they have concluded that the arrangements of matter and force are sufficient to explain it; and, on the other hand, to find theistic writers accusing physiology of materialism, if it finds the causes of vital phenomena in material forces, as if God could be present only in those processes which we can not understand.