The British chiefs, who submitted to the Romans, were subjected to a tribute or rent in corn; it varied, according to circumstances, from one fifth to one twentieth of the produce. The grower was bound to deliver it at the prescribed places. This was felt to be a great hardship, as they were often obliged to carry the grain great distances, or pay a bribe to be excused. This oppressive law was altered by Julius Agricola. The Romans patronized agriculture--Cato says, "When the Romans designed to bestow the highest praise on a good man, they used to say he understood agriculture well, and is an excellent husbandman, for this was esteemed the greatest and most honorable character." Their system produced a great alteration in Britain, and converted it into the most plentiful province of the empire; it produced sufficient corn for its own inhabitants, for the Roman legions, and also afforded a great surplus, which was sent up the Rhine. The Emperor Julian built new granaries in Germany, in which he stored the corn brought from Britain. Agriculture had greatly improved in England under the Romans. The Romans do not appear to have established in England any military tenures of land, such as those they created along the Danube and the Rhine; nor do they appear to have taken possession of the land; the tax they imposed upon it, though paid in kind, was more of the nature of a tribute than a rent. Though some of the best of the soldiers in the Roman legions were Britons, yet their rule completely enervated the aboriginal inhabitants--they were left without leaders, without cohesion. Their land was held by permission of the conquerors. The wall erected at so much labor in the north of England proved a less effectual barrier against the incursions of the Picts and Scots than the living barrier of armed men which, at a later period, successfully repelled their invasions. The Roman rule affords another example that material prosperity cannot secure the liberties of a people, that they must be armed and prepared to repel by force any aggression upon their liberty or their estates. "Who will be free, themselves must strike the blow." The prosperous "Britons," who were left by the Romans in possession of the island, were but feeble representatives of those who, under Caractacus and Boadicea, did not shrink from combat with the legions of Caesar. Uninured to arms, and accustomed to obedience, they looked for a fresh master, and sunk into servitude and serfdom, from which they never emerged. Yet under the Romans they had thriven and increased in material wealth; the island abounded in numerous flocks and herds; and agriculture, which was encouraged by the Romans, flourished. This wealth was by one of the temptations to the invaders, who seized not only upon the movable wealth of the natives, but also upon the land, and divided it among themselves.