The reasonableness of this rule is apparent the moment that its effects upon offspring are comprehended. The child inherits the joint organization of the parents. It can never be better than the sum total of the parental organizations. It may be better or worse than either of these, according to circumstances. It can never be better than both, except as education may develop possibilities as inherited from both. If, therefore, the father is capable of transmitting to the child certain vigorous elements of constitution, which were weak in the mother, and on the other hand the mother endows the child with certain graces of intellect which were deficient in the father, the result is perfection of offspring through complementary association. The same rule holds good in the matter of amiable association. When each contributes to the other, elements of character necessary to convenience and happiness, the mutual esteem and respect generated by the knowledge of the indispensableness of each to the other's interest, is the surest guard to amiability. Likewise as to financial affairs. It is easy to understand that the individual will be most successful in the affairs of life, who unites in himself all the elements of a perfect organization. Therefore, in the consummation of all partnerships, matrimonial or purely commercial, the application of this rule unites in the organization every element essential to success. In the application of this rule, it is necessary to consider, First, the character of the individual under examination; Second, the type of humanity we desire to form; Third, the ideal character necessary to the accomplishment of the end in view. The error committed by most physiologists, who have experimented with this question, lies in the fact that they have had in mind only one ideal as a perfect type of humanity, and they have tried to grade all their subjects up to this solitary ideal. Humanity, however, presents as many phases as the various climates, occupations, stages of culture, and conditions of life might be expected to produce, in various combination, and we may have a perfect type of humanity, adapted to every climate, to every occupation, to every grade of society, but differing in each. Every individual, under every condition of life, may find his proper complementary associate, adapted to the same conditions of life, but possessing a different character, harmonious with his own.