Io THE MEANING OF EVOLUTION 
pressure of what he called a perfecting principle. Out 
of the inanimate rocks had sprung the marine plants 
—the seaweeds. From these had developed first 
“plant animals” like the sea anemones and the sponges. 
These grew attached to the rocks, as plants do. With 
higher development came locornotion, with ever-in- 
creasing energy. At last man arose, the crown of all 
creation. Presiding over all this advance is the “effi- 
cient cause,” God. Aristotle rejected entirely the ear- 
lier ideas that any of this work came about by chance. 
He was certain of the existence of plan and purpose 
in the development. 
Just a little before the time of Christ the Latin 
poet, Lucretius, wrote a poem on “The Nature of 
Things.” Here he describes how in the early years 
the beginnings of things in small, disjointed fashion 
moved about among each other at first in utter con- 
fusion, each trying itself with the other. After many 
trials the proper members came together. When they 
had been thus placed the warmth of the sun shining 
down upon the earth helped the earth to reproduce 
the same sort of creatures. So living things came 
up and flourished. The poem expresses many beauti- 
ful ideas, but the underlying conceptions lack the unity 
and grandeur that marked Aristotle’s work, which 
later was the potent influence in shaping men’s minds. 
It died out after a while, only to awake in the Re- 
