But there was another most important side to the policy of the government. The ordinary conditions of daily life within the empire were certainly made much better than they had been before its establishment. It was to the interest of the government to preserve peace, an inestimable blessing to a continent which only knew the peace of exhaustion. Petty states were no longer allowed to wage war on one another. Life became more secure. The highways of the land and sea were rendered safe by the suppression of brigandage and piracy. The great roads were improved in character, to the benefit of internal trade. Moreover, to facilitate trade, and for the convenience of the revenue, Darius instituted a system of currency, whose coins were notorious for the purity of their metal. The gold Daric became, indeed, the sovereign of the ancient trading world; for the Greeks had not command of a sufficient supply of the precious metal to introduce a gold standard into their coinage system. The encouragement of agriculture, and the bringing of waste lands into cultivation, was not merely a part of the policy of the government; it was actually inculcated by the Persian religion. The revenue and taxation of the empire was conducted on business-like principles during the days of Darius; and though the burdens imposed on the subject populations were not light, yet, on the whole, they received a fair return for their contributions in the shape of that prosperity which followed upon the greater security they enjoyed. The financial levy was either in money or in kind, or in both, according to the nature and products of a province. The great defect of the system was, however, that the satraps, after handing over the provincial quota to the imperial treasury, had thereafter to raise from the province the expenses of themselves and their following. Given a strong central government and a good satrap, the system was probably as free from abuse as such a system could be; but if, as must too often have been the case, either of these circumstances were unfavourable, much evil must have resulted to the subject populations, and many of the outbreaks which took place must be assigned to such a cause.