Political philosophy as we understand it today first arose in these small-scale political communities most notably in classical Athens. Here the body of citizens was in control of its own destiny, at least as far as the internal life of the city went, so there was a great deal of point in asking questions about the best form of government, about the qualities that good rulers should posses, about the meaning of justice, and so forth. Perhaps city-states of this kind provided human beings with the best opportunity they have ever had to govern themselves well to achieve freedom, justice, and democracy. So why have they not survived? The answer is that city-states like Athens and Siena were always vulnerable to being captured and absorbed by larger units; they had constantly to be willing to fight to preserve their independence, and to do this they had to form shaky alliances with neighbouring cities, which might succeed for a time, but in the longer term proved incapable of resisting more centralized empires: Athens succumbed to Philip of Macedonia, while Siena, after preserving a modicum of independence by putting itself under the protection of nearby rulers such as the duke of Milan, was finally conquered by the Spanish Emperor Charles City-states did not fail because of their internal deficiencies, but because of their external weakness in the face of invading armies.