Many of the nations of modern Europe have a military budget relatively and absolutely greater than that of the Roman empire of the third century; but in these nations the economic system has a high degree of efficiency, compared with that of the older state, and the waste is incalculably less. The great difference lies in the slave system, which was the foundation of ancient society. The total absence of individual incentive wherever the slaves were worked in gangs—and that was, perhaps, true of the majority of slaves—made the efficiency and consequent productivity of each laborer much less. We must further remember that human waste was also much greater, owing to the absence of all measures to restrict it. Only the most elementary of sanitary precautions existed, and they were directed against definite diseases of plainly infectious character. With a great percentage of the population undernourished, the ravages of any disease with epidemic tendencies must have been enormous. Even in the absence of any plague, such a scourge as consumption alone must have been much more generally destructive than it is now. As has been recently suggested, malaria in Italy had a heavy account to answer for in producing the physical debilitation of the _populus Romanus_, and was therefore a real factor in the gradual decay of the Roman state.[389] The incidence of the state burdens was not regulated as it is at the present time. Taxes were imposed within certain districts, and upon each district devolved the duty of satisfying the impost. For a long time Italy had been free from such a burden, but even this exceptional position was abrogated by Constantine in 300 C.E. How each district accomplished its task was a local matter, and was determined by its individual development. Until the reorganization effected by Diocletian, the old national units had in the main been kept intact. That is to say, Egypt remained what it had been under the Ptolemies and for thousands of years before—a strongly centralized kingdom, rigidly bureaucratic, but measurably well organized. Asia, again, was a group of independent cities and certain larger districts, principally rural, the kingdoms of Bithynia, Cappadocia, Galatia, etc. The tax which the particular province had to deliver was apportioned among the various units according to their apparent capacity. Here and there a poll-tax existed, levied upon every inhabitant alike, and on the existence of this poll-tax far-reaching theories have been constructed.