49

Logic II 43f

physiology, by taking medicine as a halfway, out
of magic; chemistry out of alchemy, thermotics from the steam engine, etc. Among the
theoretical sciences, while some of the most abstract
have sprung straight from the concretest arts, there is
nevertheless a well marked tendency for a science
to be first descriptive, later classificatory, and
lastly to embrace all classes in one law. The classificatory
state may be skipped. Yet in the true order of
development, the generation proceeds quite in the
other direction. You Men may and do begin to study the
different kinds of animals and plants before they know
anything of the general laws of physiology. But they
cannot attain any true [know?] understanding of
taxonomic biology until they can be guided by the
discoveries of the physiologists. Till then the study of
mollusks will be nothing but such conchology. On the
other hand the physiologist may be aided by a fact
or two here and there drawn from taxonomic biology;