LIFE: ITS ORIGIN AND NATURE 
9 
THE ORIGIN OF LIFE 
From the foregoing discussion, it is evident 
that life, as we understand it, could not have 
existed from the very beginning of things on 
our planet. It must have come into being some¬ 
how or other at one time in the past, and it is 
equally certain that, at some distant date in 
the future^ it will go out of existence when the 
conditions on our planet no longer permit the 
existence of life upon its surface. Life can 
only exist between very narrow temperature- 
limits, and under a complex set or very par¬ 
ticular circumstances. The temperature-limits 
which permit physical life are the freezing and 
the boiling points of water. If the temperature 
permanently falls below or rises above these 
limits, life can no longer exist, and immediately 
passes out of being. As a matter of fact, for 
all practical purposes, the temperature limits 
are even narrower than this—being limited to 
about 100 degrees—above and below which life 
finds it extremely difficult to exist. In addi¬ 
tion to which the suitable environment must 
also be present—suitable atmospheric condi¬ 
tions, sufficient oxygen, sunlight, the right 
chemical elements, etc. 
During the many millions of years which 
must necessarily have elapsed between the time 
when our planet was a more or less incandes¬ 
cent body, and the time when it will have be¬ 
come a dead and frozen mass of matter whirling 
through space, a relatively brief period of time 
elapses, in the process of cooling, during which 
life can become manifest. It has therefore been 
