The question now arises: By what measures, or through what influences, if any, can such proneness to nervous diatheses be avoided? It may be replied, that there are two channels through which partial relief may come; but that any substantial results may follow, it will become necessary that education concerning the laws of heredity shall become more general, and the importance of right conduct in relation to them impressed especially on the minds of young persons. First.--Through the influence of that law of heredity by means of which there may occur an elimination of weaknesses and proclivities toward disease. This influence comes from the healthy side of parentage; for instance, in the case of parents, one of whom has physical or psychological tendencies toward disease, if the other has a healthy and vigorous constitution, and is endowed with mental qualities of an opposite character, these forces of the system may prove to be quite sufficient to affect or neutralize those which, on the other side of the house, lead toward disease, and the offspring may have an inheritance nearly, or quite, free from such influence. This is not unfrequently witnessed in the case even of the strongest hereditary diseases, namely those of phthisis and insanity. The offspring of mothers with proclivities toward either of these diseases, in case the father is strong, may escape entirely or nearly so; this is very often true when the well parent has an unusual power of transmitting race-characteristics, and belongs to a family which has been noted for longevity during two or three generations. In this hereditary influence there lies a power of incalculable value to the human race, a power conducing toward the elimination of morbid diatheses, which otherwise would go on increasing in almost geometrical ratio, until families, or even whole communities, would become diseased. The tendencies toward health, under favorable circumstances, are greater than toward disease, and, therefore, there exists a probability that race-characteristics on the healthy side may prevail over those on the unhealthy side of the house, though this may not always be found to be true in actual experience.