huge reptiles, or mammals of enormous strength, and by birds of
exceeding swiftness. This portion of our history covers the era of
muscular activity.

But these huge brutes are mostly doomed to extinction, and the bird
fails of supremacy in the animal kingdom. "The race is not to the
swift, nor the battle to the strong." All the time another system
has been slowly developing. The complicated nervous system has
required ages for its construction and arrangement. Only in the
highest mammals does the brain assert its right to supremacy. But
once established on its throne the brain reigns supreme; its right
is challenged by no other organ. The possibilities of all the other
organs, _as supreme rulers_, have been exhausted. Each one has been
thoroughly tested, and its inadequacy proven beyond doubt by actual
experiment. These formerly supreme lower organs must serve the
higher. The age of man's existence on the globe is, and must remain,
the era of mind. For the mind alone has an inexhaustible store of
possibilities.

The development of all these systems is simultaneous. From the very
beginning all the functions have been represented, all the systems
have been gradually advancing. Hydra has a nervous system just as
really as man. It has no brain, but it has the potentiality and
promise of one, and is taking the necessary steps toward its
attainment. But while the development of all is simultaneous, their
culmination and supremacy is successive, first stomach and muscle,
then brain and mind. That was not first which is spiritual, but that
which is natural; and afterward that which is spiritual. But now
that the mind has once become supreme, man must live and work
chiefly for its higher development. Thus alone is progress possible.

But the word mind calls up before us a long list of powers. And the
questions arise, Is one mode and line of mental action just as much
the goal of man's development as another? Is man to cultivate the
appetite for food and sense gratification just as much as the hunger
for righteousness? Or is appetite in the mind like digestion in the
body, a function, necessary indeed and once dominant, but no longer
fitted for supreme control? Is there in the development of the
mental powers or functions just as really a sequence of dominance as
in that of the bodily functions? Are there older and lower powers
and modes of action, which, though once supreme, must now be rigidly
kept down in their proper lo