oth
the physical work and the mental work of this human engine are always
accompanied by both physical and chemical changes in the structure of its
machinery--corresponding to the wear and tear of non-living engines. It
also presents certain sexual and spiritual phenomena that have a striking
likeness to certain phenomena, especially wireless phenomena, to
electricity and to radium. This human engine-battery is of unusual
strength, durability and perfection; and yet it is very liable to damage
and even wreckage, if not properly used. The controlling factors are very
delicate and so the engine is very capricious. Very special training and
understanding are necessary for its control.

The reader may wish to ask: What is the essence of the time-binding power
of Man? Talk of essences is metaphysical--it is not scientific. Let me
explain by an example.

What is electricity? The scientific answer is: electricity is that which
exhibits such and such phenomena. Electricity means nothing but a certain
group of phenomena called electric. We are studying electricity when we
are studying those phenomena. Thus it is in physics--there is no talk of
essences. So, too, in Human Engineering--we shall not talk of the _essence_
of time-binding but only of the phenomena and the laws thereof. What has
led to the development of electric appliances is knowledge of electrical
phenomena--not metaphysical talk about the electrical essence. And what
will lead to the science and art of Human Engineering is knowledge of
time-binding phenomena--not vain babble about an essence of time-binding
power. There is no mystery about the word time-binding. Some descriptive
term was necessary to indicate that human capacity which discriminates
human beings from animals and marks man as man. For that use--the
appropriateness of the term time-binding becomes more and more manifest
upon reflection.

What are the conditions of life upon this earth? Is there war or peace in
daily life? All living beings require food; they multiply in a geometrical
ratio; and so the _natural_ productivity of the soil becomes increasingly
inadequate. The tendency to increase in geometrical ratio is true of all
life--vegetable, animal and human, but the tendency is checked by various
counteracting influences, natural and artificial. A short time ago these
checks had so operated to annul the law of increase as almost to stop the
growth of human population. It is only by the time-bin