254 EVOLUTION AND THE PRESENT AGE 
Be it long or short, the next epoch-marking change 
experienced by mankind after the dawn of civilization 
was the invention of the steam engine by James Watt. 
The impulse to this stupendous invention was given 
by Joseph Black’s discovery of latent heat, one of the 
first long strides that was made into the region of 
molecular physics. From Black and Watt down to the 
latest discoveries in electricity there has been an un- 
broken sequence of achievement, and its fundamental 
characteristic has been the creation of mechanical force 
or motor energy. This has become possible through 
our increased knowledge of the interior constitution 
of matter. Having learned something about the habits 
and proclivities of atoms and molecules, we are taking 
advantage of this knowledge to accumulate vast quan- 
tities of force and turn it in directions prescribed by 
human aims and wants. This may properly be called 
creation, in the same sense that a poem or a symphony 
is created. We apply the qualities of matter to the 
achievement of results impossible save through the 
-intervention of man. 
The most striking fact about this voluntary creation 
of motor energy is the sudden and enormous extension 
which it has given to human power over the world in 
innumerable ways. It has been well said that our 
world at the present day is much smaller and more 
snug than the world in the time of Herodotus, inas- 
much as a man can now travel the whole length of the 
earth’s circumference in less time than it would have 
taken Herodotus to go the length of the Mediterranean, 
and not only in less time, but with much less discomfort 
and peril and with fewer needful changes of speech. 
This is very true, but it could not have been said a 
