The political history of ancient Greece, similarly summarised, will serve perhaps even better the purpose of illuminating later evolution. That history has served historian after historian as a means of modern polemic. The first considerable English historians of Greece, Gillies and Mitford, pointed to the evil fate of Greek democracy as a conclusive argument against countenancing democracy now; never stopping to ask whether ancient monarchies had fared any better than the democracies. And it is perfectly true that present-day democracies will tend to bad fortune just as did the ancient unless they bottom themselves more firmly and guide themselves by a deeper political science. It will not suffice that we have rejected the foundation of slavery, on which all the Greek polities rested. The strifes between the demos and the aristocracy in the Greek City-States would have arisen just as surely, though more slowly, if the demos, instead of being an upper-grade populace owning slaves, had included the whole mass of the artisan and serving class.[92] Where population increases at anything like the natural animal rate, and infanticide is not overwhelming, poverty must either force emigration or breed strife between the "have-nots" and the "haves," barring such continuous stress of war as suffices at once to thin numbers and yield conquerors the lands of the slain losers. During some centuries the pressure was in part relieved by colonisation, as had already happened among the Phoenicians;[93] the colonies themselves in turn, with their more rapid evolution, developing the inevitable strife of rich and poor more quickly and more violently than the mother cities.[94] Among these, it was when that relief seemed to be exhausted that strife became most dangerous, being obscurely perceived to be a means to advancement and prosperity for individuals, as well as for the State which could extort tribute or plunder from the others. War, however, limits agriculture, so that food supply is kept proportionately small; and with peace the principle of population soon overtakes lost ground; so that, though the Greek States like others tended to gain in solidarity under the stimulus of foreign war, the pressure of poverty was always breeding fresh division.