The rules for breeding and education set forth in the _Republic_ are not intended for the whole community, but only for the ruling minority. It was by the corruption of the higher classes that Plato was most distressed, and the salvation of the State depended, according to him, on their reformation. This leads us on to his scheme for the reconstitution of society. It is intimately connected with his method of logical definition and classification. He shows with great force that the collective action of human beings is conditioned by the division of labour; and argues from this that every individual ought, in the interest of the whole, to be restricted to a single occupation. Therefore, the industrial classes, who form the bulk of the population, are to be excluded both from military service and from political power. The Peloponnesian War had led to a general substitution of professional soldiers for the old levies of untrained citizens in Greek warfare. Plato was deeply impressed by the dangers, as well as by the advantages, of this revolution. That each profession should be exercised only by persons trained for it, suited his notions alike as a logician, a teacher, and a practical reformer. But he saw that mercenary fighters might use their power to oppress and plunder the defenceless citizens, or to establish a military despotism. And, holding that government should, like strategy, be exercised only by functionaries naturally fitted and expressly trained for the work, he saw equally that a privileged class would be tempted to abuse their position in order to fill their pockets and to gratify their passions. He proposed to provide against these dangers, first by the new system of education already described, and secondly by pushing the division of labour to its logical conclusion. That they might the better attend to their specific duties, the defenders and the rulers of the State were not to practise the art of money-making; in other words, they were not to possess any property of their own, but were to be supported by the labour of the industrial classes. Furthermore, that they need not quarrel among themselves, he proposed that every private interest should be eliminated from their lives, and that they should, as a class, be united by the closest bonds of family affection. This purpose was to be effected by the abolition of marriage and of domesticity. The couples chosen for breeding were to be separated when the object of their union had been attained; children were to be taken from their mothers immediately after birth and brought up at the expense and under the supervision of the State. Sickly and deformed infants were to be destroyed. Those who fell short of the aristocratic standard were to be degraded, and their places filled up by the exceptionally gifted offspring of low-class parents. Members of the military and governing caste were to address each other according to the kinship which might possibly exist between them.