the most powerful, producing, as it does, in the
children, an unusual liability to those maladies under which their
parents have labored.

When both parents are descended from tainted families, their progeny, as
a matter of course, will be more deeply affected than where one of them
is from a pure stock. This sufficiently accounts for the fact that
hereditary predisposition is a more common cause of nervous disease in
those circles that intermarry much with each other than where a wider
choice is exercised. Fortunately, such is the constitution of society in
this country, that there are fewer evils of this kind among us than are
manifest in many of the European states, where intermarriages are
restricted to persons of the same rank, as has already been illustrated
by reference to the grandees of Spain, who have become a race of dwarfs
intellectually as well as physically. But even in this country there are
painful illustrations of the truth of the popular belief that when
cousins intermarry their offspring are liable to be idiotic. The command
of God not to marry within certain degrees of consanguinity is, then, in
accordance with the organic laws of our being, and the wisdom of the
prohibition is abundantly confirmed by observation.

What was said of hereditary transmission in the second chapter of this
work applies here with increased force. It is of the highest possible
importance that this subject should receive the especial attention of
every parent, and of all who may hereafter sustain the parental
relation; for posterity, to the latest generations, will be affected by
the laws of hereditary transmission, whether those laws are understood
and obeyed or not. The importance of this subject, already inconceivably
vast, becomes infinitely momentous in view of the probability that the
evils under consideration are not confined to this life, but must, from
the nature of the case, continue to be felt while mind endures.

Unfortunately, it is not merely as a cause of disease that hereditary
predisposition is to be dreaded. The obstacles which it throws in the
way of permanent recovery are even more formidable, and can never be
entirely removed. Safety is to be found only in avoiding the
perpetuation of the mischief. When, therefore, two persons, each
naturally of an excitable and delicate nervous temperament, choose to
unite for life, they have themselves to blame for the concentrated
influence of similar tendencies in