The essence of all religions is the recognition of an Authority higher, more comprehensive, more permanent than the human being. The characteristic of Christian teaching is the faith that this Supreme Authority is beneficent as well as powerful. The Christian believes that the Creative Force is a moral force, of more comprehensive morality than the human being that it creates. Under the symbol of a wise and loving parent--the most just, efficient, and attractive image that we know of--we are encouraged to regard this unseen Authority as being in direct relation with every atom of creation, and as desirous of drawing each atom into progressively higher forms of existence. The Christian physiologist, therefore, knowing that there is a wise and beneficent purpose in the human structure, seeks to find out the laws and methods of action by means of which human function may accomplish its highest use. The task can only be carried out gradually. Ultimate function is not revealed by structure, nor ultimate use by function. The empty arteries did not suggest the circulation of the blood to ancient physiologists, nor did the curious arrangements of the intestinal canal explain the complicated function of digestion. Ignorance of facts, preconceived notions, or fanciful theories as to ‘vital spirits,’ ‘cold and hot humours,’ etc., long delayed the attainment of correct knowledge of physiological facts. Neither does physical knowledge of individual function reveal the developed use of which it is capable. The new life that may be given through touch to the blind, or the destruction of a nation through its vices, is not revealed by the minutest examination of the mechanism of touch, or the physical structure of the nervous system. Function and use are only proved by observation, reflection, and rational experiment patiently carried on age after age, with generalization based upon accurate and accumulated facts. Structure, function, and extended use, although closely connected, are, nevertheless, separate branches of inquiry. Applied physiology comprehends them all. Function is the arrangement by means of which the independent life of the sentient being is carried on and maintained. Developed function or use includes the growth and improvement of the individual in relation to his fellows, and to existence outside his own personality.