By comparison with the Moslem Institution, the Ruling Institution possessed a great structural disadvantage, in that it was much more artificial and therefore much less stable. It admitted its members as slaves, but they were not hereditary slaves; most of them were free-born subjects of the empire or of the neighboring Christian states. A class of hereditary slaves would not have possessed the requisite mettle. Now, the acquisition of a large number of free-born children who can be made into slaves is hardly a process that can be continued indefinitely. Conquest had its limits for the Ottoman Empire, for boundaries were reached beyond which lay states whose powers of self-defense developed increasingly; accordingly, recruiting by capture became increasingly difficult. But the levying of children as tribute was strongly against human nature; and in the long run it, too, must lead to decline, for under its operation the best were taken and inferiors were left. Furthermore, not only were children separated from their parents against the wishes of the parents, but the recruits, when they grew up, were not encouraged to form family ties. Even when they did so, they were unable to advance their children as they had been advanced themselves, and they could not be sure of conveying their property to their descendants. Thus in several respects the Ruling Institution ran counter to the idea of the family. On the other hand, the advantages given to the sultan’s _kullar_ became too great not to be coveted; and it was not natural that the free-born Moslems should continue to let outsiders be the only recipients of so much wealth, power, and privilege. The Moslem population forced its way in, and the plan of the Ruling Institution was upset. The Moslem Institution, on the contrary, was recruited voluntarily from an increasing population; hence, as its advantages became attractive, it was benefited rather than harmed by pressure for admission. Its able men, while they must labor if they would advance, were free, unhindered in their family relationships, and under little fear of being deprived of property or life. INTERACTIONS The two institutions, running everywhere parallel, with their members in constant association one with the other, could not fail to act reciprocally upon each other. It is not easy, however, to discriminate likenesses that were due to mutual influence from those that were caused by common circumstances; nor is it easy to distinguish pre-Ottoman interactions from those which operated after the beginning of the fourteenth century. A few probabilities may be expressed, however.