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ON DEATH. 459
Even the natural duration of the life of man upon the
earth, is but vaguely known. The proverb, "
seventy
years is allotted to man," is but the expression of an ob
servation of ordinary longevity. But that there is really
any providential allotment of such a period, is contrar
dieted by the fact that a large proportion of mankind
perish in infancy, while some live a century, and even
a century and a half.
Of the several periods of human life, some have a
definite duration, while others are indefinitely extended.
The periods of infancy, childhood, and youth, are
marked by striking physical phenomena, and vary but
little in their length. It is the same with senility. The
failure of the powers of life, when it once begins, is
regular and rapid. But there is one stage of existence,
which may be cut short, or indefinitely prolonged. This
is the period of manhood, or the full perfection of ex
istence. It. may last for ten or or a
years, fifty, hun
dred. We know not to what duration it may possibly
extend.
But, when the uses of the bodily organism have been
comes the inevitable death. The stock
fully answered,
ef organic vitality is finally expended.
The heart can
not beat on forever ; not from any lack of its own powers
of recuperation, but from the failure of nervous energy
in the centers of organic life.
In the process of death, we have the reverse of the
process of development. First fail the generative func
tions ; next, the animal: lastly, the organic. Still, I be
lieve that each of the former fails, in its turn, from the
diminished power of the last. And finally, in the act
of death, the system of animal life—of passion, thought,