Plato saw that the rulers when once selected and installed in office would be tempted to become avaricious at the expense of the state. Instead of becoming and remaining allied to all the citizens, they will be prone to become tyrannical.[V-27] Plato perceived that it would be difficult, after good rulers had been selected, to keep them on the plane of good rulership. In order to preserve their virtue as guardians and to remove the powerful temptation to wink at exploitation that is carried on by the economically powerful, Plato indicated certain protective devices. The guardians shall be permitted no private property beyond a few incidentals. They shall not live in private houses, but shall dwell and eat together. They shall receive a fixed salary, sufficient to meet necessary expenses but no more. They shall not be allowed to touch gold and silver or to wear gold and silver ornaments. They shall be taught that they are made of divine gold and silver, and therefore shall have no need of the earthly dross. They shall not be subject to pollution from any earthly contacts. If the guardians should acquire lands or moneys or homes of their own, they would be unable to give their undivided attention to the state, and they would become not guardians of the welfare of the citizens, but tyrants, plotting and being plotted against.[V-28] In his zealous care that the rulers might not be distracted from guarding with undivided attention the interests of the state, Plato advocated community of wives and children for the rulers.[V-29] The question arose: Will the people be content to accept the division of the population into hierarchal classes? In reply, Plato suggested that the power of public opinion be utilized, and that all the inhabitants of the state be taught that they are brothers, that is, children of their common Mother Earth. This instruction will serve to keep the masses in a humble attitude. Further, they are to be told that different metals have been used by Mother Earth in making different individuals. Those persons in whose make-up gold has been mingled have the power of command and may become rulers. Others who are made of silver may become auxiliaries, or soldiers; while the masses, being made of brass and iron, are destined to become artisans.[V-30] The objection is raised that people will not believe this “audacious fiction.” The truth of the objection is admitted, and a solution of the problem is offered. Teach the children the gold, silver, brass and iron fiction; and they will believe it. When they grow to maturity, they will tell their children, who in turn will teach it. Posterity, thus, will accept it.[V-31] In this way Plato founded his social philosophy upon education. Plato made clear that any kind of social or economic theory can be foisted upon a whole people through the utilization of the educational processes. A few selfish exploiters, by controlling the educational system, can ruin a nation in a generation.