The Psalmist considered three score years
and ten the natural life of man. This has ever
since been accepted as a fair measure of what
ought to be the length of human life, barring
accidents. We believe this measure to be too
short by thirty years.
It is a fair general principle in natural his-
tory that the animal should live five times the
length of the period of its development from
birth to complete maturity. Thus the horse,
which comes to its perfect maturity at from
five to six years of age, may safely be counted
upon, if properly cared for, to live from
twenty-five to thirty years. Individual ex-
ceptions need not be considered. According
to this principal, the life of man should be
about one hundred years, if accidental causes
of premature death are eliminated.
One requirement necessary to the attain-
ment of the condition most favorable to long