Upon Melanchthon, the consent to the double marriage of the Duke must have been less hard. Before that, he had written to Henry VIII "every Prince has the right to introduce polygamy in his domains." But the double marriage of the Duke made such a great and unpleasant sensation, that, in 1541, he circulated a treatise in which polygamy is defended as no transgression against Holy Writ.[53] People were not then living in the ninth or twelfth century, when polygamy was tolerated without shocking society. Social conditions had very materially changed in the meantime; in a great measure the mark had had to yield to the power of the nobility and the clergy; it had even extensively disappeared, and was further uprooted after the unhappy issue of the Peasant Wars. Private property had become the general foundation of society. Beside the rural population, that cultivated the soil, a strong, self-conscious handicraft element had arisen, and was dominated by the interests of its own station. Commerce had assumed large dimensions, and had produced a merchant class, which, what with the splendor of its outward position and its wealth, awoke the envy and hostility of a nobility that was sinking ever deeper into poverty and licentiousness. The burghers' system of private property had triumphed everywhere, as was evidenced by the then universal introduction of the Roman law; the contrasts between the classes were palpable, and everywhere did they bump against one another. Monogamy became, under such conditions, the natural basis for the sexual relations; a step such as taken by the Duke of Hessen now did violence to the ruling morals and customs, which, after all, are but the form of expression of the economic conditions that happen at the time to prevail. On the other hand, society came to terms with prostitution, as a necessary accompaniment of monogamy, and an institution supplemental thereto;--and tolerated it.