Aristotle believes that the number of friends should be limited because true friendship takes time. In battle, Plato agrees that if the enemy is also Greek, then precautions should be taken regarding land and killing, however if the enemy is not Greek, then there are no borders. Plato believes that knowing what is right will automatically lead to doing the right thing, while Aristotle believes that it is not enough to just know what is good, the person must still make the right choice. Plato believed that virtue was not obligatory for a somewhat primitive type of happiness, however Aristotle believed that virtue was necessary. Plato fundamentally believed that all virtues boiled down to wisdom, and Aristotle believed that virtue must be practiced and that one can still be virtuous and unhappy. Socrates points out that everyone is considered family and that in the perfect state there will be no divided loyalties. Furthermore, private property, responsible for fiefdoms, would not exist. Plato's teacher, Socrates, believes that a philosopher should become a ruler, or that the current ruler should learn philosophy, since philosophers are more aware of how to manage the state. However, Aristotle believes that all sophists should stay out of it