is of potential and kinetic use-values a little
further. All potential use-values left to us by the dead are temporal and
differ in utility. Many potential use-values are found in museums and have
very limited value to-day in practical life. On the other hand some roads
or water-ways built by the ancients have use-value to-day; and an almost
endless list of modern potential use-values have or will have use-values
for a long time to come, such as buildings, improved lands, railroad
tracks, certain machines or tools; the use-value of some such items of
material wealth will last for more than one generation. Kinetic use-values
are permanent in their character, for, though they may become antiquated,
they yet serve as the foundation for the developments that supersede them,
and so they continue to live in that to which they lead.

I would draw attention at this point to one of the most important kinetic
and potential use-values produced by humanity--the invention of the steam
engine. Through this invention, humanity has been able to avail itself,
not only of the living fruits of dead men's toil, but also of the
inconceivably vast amounts of solar energy and time bound up in the growth
of vegetable life and conserved for use in the form of coal and other
fuels of vegetable origin. This invention has revolutionized our life in
countless directions. To be brief, I will analyse only the most salient
effects. Human Engineering has never existed except in the most embryonic
form. In remote antiquity the conception and knowledge of natural law was
wholly absent or exceedingly vague. Before the invention of the steam
engine, people depended mainly upon human powers--that is, upon "living
powers"--the powers of living men, and the living fruits of the labor of
the dead. Even then there were manifold complications.

The invention of the steam engine released for human use a new power of
tremendous magnitude--the stored-up power of solar energy and ages of time.
But we must not fail to note carefully that we to-day are enabled to use
this immense new power of bound-up solar energy and time by a human
invention, a product of the dead.

The full significance of the last statement requires reflection. The now
dead inventor of the steam engine could not have produced his ingenious
invention except by using the living powers of other dead men--except by
using the material and spiritual or mental wealth created by those who had
gone before