sistant to the action of several drugs, which simplifies such work still further. In thus employing the unstable coal-tar products to destroy organisms made up of labile protoplasm, Ehrlich has opened up an entirely new field of therapeutics. As Morgagni, the first pathologist, treated of the seats and causes of disease (De sedibus et causis morborum), so Ehrlich has sought (he claims) to gain a fuller knowledge of the distributive and local causal relations of the finest mechanism of drugs, de sedibus et causis pharmacorum.
In deploying this vast chemical knowledge against protozoan disease Ehrlich has been likened to a general who aims to take a fort by investing it on all sides. In the other important respect he resembles a great commander—in the possession of an imagination lively and keen enough to figure out the enemy's possible movements as the first step towards checkmating him. The true fighter always respects his adversary, and Ehrlich, who, in profile, looks so much like Thomas Carlyle, has taught physicians to have a very wholesome respect for their adversary, the disease germ. He has seen and demonstrated that the parasites of disease can protect themselves against man's attacks, that in this respect they are as wary and fertile in resource as we. In the future history of medicine he will have his high place as the most original thinker of his time in regard to the nature of infectious disease, as a leader in synthetic chemistry, and as a foremost champion in humanity's "Kulturkampf gegen den Tod."
- Ehrlich, Harben Lectures ("Experimental Researches in Specific Therapeutics"), London, 1908, 88.