Of all the influences which have most to do in the making of an
individual, heredity is perhaps the greatest. It is the crucible in which
the gold and dross of many generations of his ancestors are melted down
and remixed in the man, who is, indeed, "a part of all" from whom he
claims descent.

There is no more engrossing study than to trace back through many a
century of ancestors, the various--often conflicting--elements which go to
make up the character of someone whose life (without the clue given by the
history of his forbears) is often a strange contradiction. Unable to
understand some disability which spoils an otherwise fine personality, one
looks back and there is the explanation. One's finger rests on the _raison
d'etre_ of this disability. Long since it had its birth, its inauguration,
in the squeeze, so to speak, into that strange crucible, of the taint, the
essence, of some ancestor's moral lapses, or of the effect of his moral,
mental, or physical ill-health.

Dr. Maudsley says very definitely that the faults, the disabilities, of
men and women of to-day, are sometimes an undesirable inheritance. "Mental
derangement in one generation is sometimes the cause of an innate
deficiency, or absence of the moral sense in the succeeding generation."

I remember once hearing a London doctor strongly emphasize the need for
every family to keep a careful, conscientious family record book, which
from generation to generation should act as a _vade mecum_--showing what
failings must be fought at all costs, and what connections avoided, if we
would not perpetuate disease. Such a thing, if done universally, might
check many national evils in our midst to-day.