296 Egypt and Rome was the maintenance of irrigation works; and even to-day the government of Egypt is entitled to call out every able-bodied man to guard the banks of the Nile in flood. Nevertheless the right of the government to the labour of its subjects remained latent, and on emergency the Ptolemies did not hesitate to use it. Thus when they failed to lease royal land at a rent agreeable to their ideas they are known on occasions to have conscripted the peasants to cultivate it. Such measures were rare under the Ptolemaic regime, but under Roman rule they became about normal. The Ptolemies squeezed the last penny of revenue out of Egypt, it is true, but they did allow a sufficient margin of profit to their subjects to make them willing to work for them. The Romans were more exact- ing: whether they over-estimated the productivity of Egypt or whether its prosperity declined for other reasons under their rule, the demands of the Roman government often left so small a balance to their subjects that they had no incentive to work. Undeterred, the Romans, instead of adjusting their demands, resorted to compulsion. In agriculture this took two main forms. Public land for which no tenant would bid the rent demanded by the government might be compulsorily allocated to the village community, which sublet it on the best terms it could get and shared out the deficit. Alternatively it might be allocated to a private landowner, who had to pay its rent out of the profits of his own more lightly taxed land. Both methods were in the Byzantine age applied extensively throughout the empire to the problems of collecting the rent on imperial estates and the tribute on private land: and as economic decline and the consequent difficulty of keeping land under cultivation, or rather of extracting the revenue due from uncultivated land, began far earlier in Egypt than elsewhere, it is a reasonable pre- sumption that the imperial officials of the Byzantine age were inspired by the precedents set by the Roman administration in Egypt.