28 LIFE: ITS ORIGIN AND NATURE 
physical movement is involved, which can 
readily be perceived by other individuals. Life, 
however, may be intensely active, without any 
visible expression of such activity. For ex¬ 
ample, a person may sit still in a chair, and 
think intently. Great activity may be going on 
within the brain. But this is totally invisible 
to a bystander. Life itself is always invisible, 
and we merely infer its presence by reason of 
certain physical activities, which are visible 
or manifest to us. But this is by no means a 
just criterion. A man may be paralyzed, and 
yet intently alive within himself. He merely 
lacks the means for physical expression, in the 
material world, of this life-activity. Thought 
and emotion also represent active manifesta¬ 
tions of life, but they are invisible, or hidden. 
One of the most characteristic factors of life 
is its desire to perpetuate itself. The stream of 
life must be perpetuated, even if the individual 
perishes! This is seen in many of the lower 
organisms which perish at the very moment 
that active reproduction has been accomplished. 
Among the manifestations of life, we must 
therefore include this remarkable desire to per¬ 
petuate and to reproduce* itself. Next to self- 
preservation, it is the most powerful force in 
animate nature. 
THE REGULATORS OF LIFE 
The life of the body is not a blind force. It 
acts toward certain “ends.” When actions are 
performed in the body, they are for a specific 
purpose. In this sense, all life is “teleological;” 
it acts towards a specific end and with a 
