of development made tribal life possible, it cannot have been
usual for man to have knowledge of his grandparents; as a rule he
did not know his own parents after he had passed the adolescent
stage and had been turned out upon the world to care for himself.
If, then, certain of his fellow-beings showed those evidences of
infirmity which we ascribe to age, it did not necessarily follow
that he saw any association between such infirmities and the
length of time which those persons had lived. The very fact that
some barbaric nations retain the custom of killing the aged and
infirm, in itself suggests the possibility that this custom arose
before a clear conception had been attained that such drags upon
the community would be removed presently in the natural order of
things. To a person who had no clear conception of the lapse of
time and no preconception as to the limited period of man's life,
the infirmities of age might very naturally be ascribed to the
repeated attacks of those inimical powers which were understood
sooner or later to carry off most members of the race. And
coupled with this thought would go the conception that inasmuch
as some people through luck had escaped the vengeance of all
their enemies for long periods, these same individuals might
continue to escape for indefinite periods of the future. There
were no written records to tell primeval man of events of long
ago. He lived in the present, and his sweep of ideas scarcely
carried him back beyond the limits of his individual memory. But
memory is observed to be fallacious. It must early have been
noted that some people recalled events which other participants
in them had quite forgotten, and it may readily enough have been
inferred that those members of the tribe who spoke of events
which others could not recall were merely the ones who were
gifted with the best memories. If these reached a period when