I do not suppose it likely that any of my readers will marry a negress, Hottentot, or Australian savage, so I need not speak of the hybridism of races, or the consequences of the possible unions. If, before I die, I have the supreme joy of writing my monograph on man, my _microcosm_; then I shall be able to tell you my ideas about it, confessing to you at once my profession of faith, which is this, that all those who deplore the effects of the union of races, saying it is always injurious to the future generations, are mistaken; as well as those of the opposite school, who always proclaim it to be useful. The crossing of a superior race with an inferior one lowers the first and elevates the second, thus giving a product of _medium_ goodness. The union of two races equally superior, generally gives an inferior product, but a product different from the two types who have fused their blood in the crucible of love. The union of a mediocre and elevated race, produces very different effects, according to conditions. These, however, are as yet little known, and must be studied by degrees. If, however, you will never marry a negress, nor a redskin, and very probably neither a Chinese nor Japanese, it is easy enough for you to become enamoured of an English, German, or Spanish woman: and in the present day, when railways and telegraphs bring nations so near together, and break down barriers; marriage is preparing the way for the future _United States of Europe_, which will certainly become the keystone of a cosmic republic, that of the _Civilized States of the World_. The differences of type and sympathy between opposite natures easily prompt to a warm love between dark and fair nations. More than one Italian has been obliged to fly from Scandinavia on account of the excessive sympathy which he awakened in those fair innocent daughters of the Edda; and if a fair-haired son of Arminius goes into Spain or South America, it is very seldom that he returns to his mother country without a wife, or without great spoils won in the mighty victories of love. Is this a good? Is it an evil? For the children it is nearly always a benefit; for married people it is often an evil. The felicity of husband and wife is sacrificed to the species, and it is your duty to set these different, but probable, consequences of union in the balance and weigh them. The differences which we sum up under the word nationality, are not as marked as race differences, but they approach them; nationality is always and in every way the complex sum of infinite physical, moral, and intellectual elements which make an Englishman so different from a Spaniard, and an Italian so unlike a Norwegian.