In primitive societies, where private property is yet unknown, or still undeveloped, there are no class distinctions, no class domination, and no class antagonisms. The chief, the medicine man, and the judge regulate or supervise the observance of the customary usages, religious ceremonies, and social arrangements. But as soon as the old order is dissolved, and private property develops, in consequence of trade with other peoples or through wars, there arise classes of those who possess and those who do not. The possessing class carries on the Government, makes laws, and creates institutions, which chiefly serve the end of protecting the interests of the possessing and ruling classes. The intellectual structure of the class society likewise corresponds to the interests of those who possess and rule. So long as these interests promote the common good in some measure, so long as the old forms of production and the old conditions of production are largely in harmony with each other, a certain truce prevails between the classes. But should there set in the above-mentioned opposition between the productive forces and the conditions of production, the latter will cease to satisfy the oppressed classes, and class conflicts will arise, which will either result in legal compromises (reforms) or will end in the overthrow of the society concerned, or will lead to a new set of conditions. Ancient history (Hebrew, Greek, Roman) is full of these social struggles; all the great reform laws of these peoples were attempts to establish social peace, but the rich and the poor, the Patricians and the Plebeians, the Slaves and Freemen, continued their struggles until the downfall of the old world, which has bequeathed to us great intellectual treasures as the fruit of these struggles. In the Middle Ages social struggles between the feudal lords and the traders, between nobles and peasants, were kindled. In more recent times the middle classes fought Autocracy and Squirearchy, and at length the proletariat was pitted against the bourgeoisie--class struggles which led to rebellions and revolutions, and powerfully influenced the intellectual life.