ight or
some other physical manifestation. But the energy of foodstuffs which a
man uses up in a mental effort does not appear again in the circuit of
the law of the conservation of energy. A man uses up more energy in his
waking moments, though his body be passive, than in his sleeping. What
we call mental force cannot be accounted for in terms of physical force.
The sun's energy goes into our bodies through the food we eat, and so
runs our mental faculties, but how does it get back again into the
physical realm? Science does not know.

It must be some sort of energy that lights the lamps of the firefly and
the glow-worm, and it must be some sort or degree of energy that keeps
consciousness going. The brain of a Newton, or of a Plato, must make a
larger draft on the solar energy latent in food-stuffs than the brain of
a day laborer, and his body less. The same amount of food-consumption,
or of oxidation, results in physical force in the one case, and mental
force in the other, but the mental force escapes the great law of the
equivalence of the material forces.

John Fiske solves the problem when he drops his physical science and
takes up his philosophy, declaring that the relation of the mind to the
body is that of a musician to his instrument, and this is practically
the position of Sir Oliver Lodge.

Inheritance and adaptation, says Haeckel, are sufficient to account for
all the variety of animal and vegetable forms on the earth. But is there
not a previous question? Do we not want inheritance and adaptation
accounted for? What mysteries they hold! Does the river-bed account for
the river? How can a body adapt itself to its environment unless it
possess an inherent, plastic, changing, and adaptive principle? A stone
does not adapt itself to its surroundings; its change is external and
not internal. There is mechanical adjustment between inert bodies, but
there is no adaptation without the push of life. A response to new
conditions by change of form implies something actively
responsive--something that profits by the change.

VII

If we could tell what determines the division of labor in the hive of
bees or a colony of ants, we could tell what determines the division of
labor among the cells in the body. A hive of bees and a colony of ants
is a unit--a single organism. The spirit of the body, that which
regulates all its economies, which directs all its functions, which
cooerdinates its powers, which brings a