Having thus touched upon the general subject of the relations of chemistry to materia medica and to hygiene, it remains for me to consider briefly the relations between chemistry and medicine in a deeper and broader sense. We can not at the present day, like our predecessors, regard medicine as a branch of chemistry. There are many kinds of action, not chemical, which must be studied and understood by the physician. Still, undoubtedly many of the physiological processes are essentially of a chemical nature, and there are many pathological phenomena which are also chemical. The complex organism which is the physician's field of work employs a variety of forces, prominent among which is the chemical force. It would be a trite remark to say that the physician can not possibly have a complete comprehension of what is going on within the body without a fair knowledge of chemistry. Yet I fear this fact is not always fully realized, nor indeed generally, if we are to take as evidence the practice of most medical schools.
Writing a quarter of a century ago, Liebig used these words, which I can not do better than to repeat: "Physiological and chemical researches in the field of medicine are only in their infancy, but scarcely begun; they have furnished the conviction that the processes in the living body rest upon natural laws, and every day brings discoveries, which prove that these laws can be investigated. It is true that in ages gone by there were excellent physicians who knew nothing of anatomy, and that for centuries diseases have been cured, the nature of which was not understood, just as to-day the nature of 'fever' and 'inflammation' is not known; but there is not the slightest foundation for the conclusion that an exact insight into these processes is impossible." And again he says: "Without correct ideas in regard to force, cause, action; without a practical insight into the nature of natural phenomena; without a thorough physiological and chemical training, it is no wonder that otherwise sensible men defend the most nonsensical views."
These words of Liebig are just as forcible to-day as the day they were written, and just as applicable.
The special value of a training in chemistry for a physician does not necessarily depend upon the fact that he learns a host of useful things, that he learns how to analyze substances, etc. To be sure, these acquisitions are valuable to him. But, if chemistry is to do for him what it can do, he must work so long and so conscientiously in its field as to enable him to acquire the "chemical sense." He must learn to think in the language of chemistry. He must reason as chemists reason—not as deeply, of course, but in the same general way. Then chemistry will be to him a constant aid, whose presence he will feel whenever he is brought face to face with life, either in its normal or its abnormal forms.
But, even if he did not retain a single chemical fact, the training
