The forms of Society which replace one another are, in the opinion of Ibn Khaldûn; 1) Society in the Nomad condition; 2) Society under a Military Dynasty; and 3) Society after the City type. The first question is that of food. Men and nations are differentiated by their economical position, as nomads, settled herdsmen, agriculturists. Want leads to rapine and war, and to subjection to a monarch who will lead them. Thus dynastic authority is developed. This again founds for itself a city, where division of labour or mutual assistance produces prosperity. But this prosperity leads to degenerate idleness and luxury. Labour has in the first place brought about prosperity; but now, at the highest stage of civilization, men get others to labour for them, and often without any direct equivalent, because regard or even servility to the upper classes, and extortionate treatment of the lower, secure success. But, all the same, men are coming to depend upon others. Needs are always growing more clamant, and taxes more oppressive. Rich spendthrifts and tax-payers grow poor, and their unnatural life makes them ill and miserable. [20] The old warlike customs have been refined away, so that people are no longer capable of defending themselves. The bond,—formed by a sense of belonging to one community, or the bond of Religion,—by the help of which the necessity and the will of the chief knit the individual members together in older days, is relaxed, for the citizens are not pious. Everything, therefore, is ready to break up from within. And then appears a new and powerful nomad race from the desert, or a people not so greatly over-civilized, but possessed of a firmer public spirit; and it falls upon the effeminate city. Thereafter a new State is formed, which appropriates the material and intellectual wealth of the old culture, and the same history is repeated. It fares with States and the larger associations of men, just as with single families: their history is brought to a close, in from three to six generations. The first generation founds; the second maintains, as perhaps the third or even farther generations also do; the last demolishes. That is the cycle of all civilization.