In civilized Europe mental culture progresses in the direction of equality of rights between the two sexes, so that a man regards his wife more as a companion who is his equal and no longer a slave. Community of interests, opinions, sentiments and culture constitute a primary condition for sentiments of mutual sympathy and favors affection. No doubt, excitation of the sexual appetite by contrasts acts here as an antagonistic force. Contrast should not be so great as to exclude sympathy. Too great difference in age is dangerous for attachment, for it causes too great a divergence in the aims and interests of life. Education and social equality also favors love, and this tends to preserve class distinction. It is rare for a well-educated man to fall in love with a peasant, or a laboring man with an educated woman, except in a sensual way. Men generally avoid marriage with individuals of another race, or of another religion. Endogamy and exogamy do not form such an absolute contrast as at first sight might appear. Even among exogamous races, there is a limit which must not be passed. These races often prohibit marriage with individuals of another race. Among the Arabs, for example, the instinct of ethnical separation is so strong, that the same Bedouin wife who will prostitute herself for money with Turks or Europeans, would think it dishonorable to marry one of them. In this way custom produces endogamy of caste and class among the same people. The same with the nobility; in ancient Rome it was forbidden for a patrician to marry a plebeian. Sometimes an endogamy of religious origin is met with, among the Jews for example. Children are treasures for the man of low culture, while they become a burden to the cultivated man. In spite of this the natural man ardently desires children. In Switzerland, two-fifths of the divorces occur in sterile unions, although the latter only form one-fifth of all marriages. Calculation often smothers sentiment when it becomes the basis of marriage. We live to-day under the sway of Mammon, with the result that the influence of love, strength, beauty, capacity for work, intelligence, skill, character and even health, count for little compared with money in the question of marriage. This sad sign is really a new form of marriage by purchase, hypocritically disguised. MARRIAGE BY RAPE AND MARRIAGE BY PURCHASE The rape of women is an established custom in some regions. Certain marriage ceremonies prove that rape was formerly much more common than at the present day. Among certain Indian tribes the simulation of rape and abduction of the woman form part of the marriage ceremonies; custom requiring that the woman must feign to resist.