Yet all this time the old method of inductive observation has not gone dead.  Most magnificent triumph of nineteenth century science, the evolution theory of Charles Darwin, remains the most conspicuous instance of clarification of thought in human history.  That work was the outcome of an attempt to relate and interpret a collection of observations on species and their variations, that had long lain to hand, a mixture without a solvent.  Darwin saw certain generalizations as solvents, and behold! a clear solution out of the mud.  But it was by piling evidence upon evidence, co-ordinating isolated facts not directly associated, that the towering structure was erected.  There is no prettier sample extant of the powers of the inductive method.

Not that there are no triumphs of the quantitative method in store for the biologist.  Already, the materials of the Mendelians have become basic parts of his structure.  And today, in pursuit of the solutions of hundreds of the problems of living matter, chemists and physiologists are employing the most precise standards, units, and measures of the physical sciences.  Blood chemistry of our time is a marvel, undreamed of a generation ago.  Also, these achievements are a perfect example of the accomplished fact contradicting a priori prediction and criticism.  For it was one of the accepted dogmas of the nineteenth century that the phenomena of the living could never be subjected to accurate quantitative analysis.

However desirable the purely quantitative experimental methods may be, they naturally need always to be preceded by the qualitative studies of direct observations.  Inevitably there will be numberless errors, apparent and real inconsistencies and contradictions, and ideas that will have to be discarded.  Just the same there is no other method of progress.  Every bit of evidence points towards the internal secretions as the holders of the secrets of our inmost being.  They are the well springs of life, the dynamos of the organism.  In trailing their scent we appear to be upon the track not only of the chemistry of our bodies, but of the chemistry of our very souls.  An increasing host of factors and studies marshal themselves solidly for that declaration.  Endeavor to conceive the consequences and possibilities for the future.  A synthesis of the known in the field provides even now a means of understanding and control of the perplexities of human nature and life that are like a vista seen from a mountain top after the lifting of a fog.

The most precious bit of knowledge we possess today about Man is that he is the creature of his glands of internal secretion.  That is, Man as a distinctive organism is the product, the by-product, of a number of cell factories which control the parts of his make-up.  Much as the different divisions of an automobile concern produce the different parts of a car.  These chemical factories consist of cells, manufacture special substances, which act upon the other cells of the body and so start and determine the countless processes we call Life.  Life, body and soul emerge from the activities of the magic ooze of their silent chemistry precisely as a tree of tin crystals arises from the chemical reactions started in a solution of tin salts by an electric current.