CHAPTER VI 
LINN-EUS AND SCIENTIFIC NATURAL HISTORY 
WE turn now from the purely anatomical side to consider 
the parallel development of the classification of animals and 
of plants. Descriptive natural history reached a very low 
level in the early Christian centuries, and remained there 
throughout the Middle Ages. The return to the writings of 
Aristotle was the first influence tending to lift it to the position 
from which it had fallen. After the decline of ancient civili- 
zation there was a period in which the writers of classical 
antiquity were not read. Not only were the writings of the 
ancient philosophers neglected, but so also were those of the 
literary men as well, the poets, the story-tellers, and the his- 
torians. As related in Chapter I, there were no observations 
of animated nature, and the growing tendency of the educated 
classes to envelop themselves in metaphysical speculations 
was a feature of intellectual life. 
The Physiologus or Sacred Natural History.— During this 
period of crude fancy, with a fog of mysticism obscuring all 
phenomena of nature, there existed a peculiar kind of natural 
history that was produced under theological influence. The 
manuscripts in which this sacred natural history was em- 
bodied exist in various forms and in about a dozen languages 
of Eastern and Western Europe. The writings are known 
under the general title of the Physiologus, or the Bestiarius. 
This served for nearly a thousand years as the principal 
source of thought regarding natural history. It contains 
110 
