• As soon as we touch the complex processes that go on in a living thing, be it plant or animal, we are at once forced to use the methods of this science [chemistry]. No longer will the microscope, the kymograph, the scalpel avail for the complete solution of the problem. For the further analysis of these phenomena which are in flux and flow, the investigator must associate himself with those who have labored in fields where molecules and atoms, rather than multicellular tissues or even unicellular organisms, are the units of study.

    John Jacob Abel, Otto Folin, Theobald Smith (1915). “Experimental and chemical studies of the blood: with an appeal for more extended chemical training for the biological and medical investigator”