CHAPTER XIX 
THE RISE OF EVOLUTIONARY THOUGHT 
A CURRENT of evolutionary thought can be traced through 
the literature dealing with organic nature from ancient times. 
It began as a small rill among the Greek philosophers and 
dwindles to a mere thread in the Middle Ages, sometimes 
almost disappearing, but is never completely broken off. 
Near the close of the eighteenth century it suddenly expands, 
and becomes a broad and prevailing influence in the nine- 
teenth century. Osborn, in his book, From the Greeks to 
Darwin, traces the continuity of evolutionary thought from 
the time of the Greek philosophers to Darwin. The ancient 
phase, although interesting, was vague and general, and 
may be dismissed without much consideration. After the 
Renaissance naturalists were occupied with other aspects of 
nature-study. They were at first attempting to get a knowl- 
edge of animals and plants as a whole, and later of their 
structure, their developments, and their physiology, before 
questions of their origin were brought under consideration. 
Opinion before Lamarck.—The period just prior to 
Lamarck is of particular interest. Since Lamarck was the 
first to give a comprehensive and consistent theory of evolu- 
tion, it will be interesting to determine what was the state 
of opinion just prior to the appearance of his writings. 
Studies of nature were in such shape at that time that the 
question of the origin of species arose, and thereafter it would 
not recede. This was owing mainly to the fact that Ray and 
Linneus by defining a species had fixed the attention of 
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