I. In a great empire like that of Rome, a natural balance of money must have gradually established itself. It has been already observed, that as the wealth of the provinces was attracted to the capital by the strong hand of conquest and power, so a considerable part of it was restored to the industrious provinces by the gentle influence of commerce and arts. In the reign of Augustus and his successors, duties were imposed on every kind of merchandise, which through a thousand channels flowed to the great centre of opulence and luxury; and in whatsoever manner the law was expressed, it was the Roman purchaser, and not the provincial merchant, who paid the tax. The rate of the customs varied from the eighth to the fortieth part of the value of the commodity; and we have a right to suppose that the variation was directed by the unalterable maxims of policy; that a higher duty was fixed on the articles of luxury than on those of necessity, and that the productions raised or manufactured by the labor of the subjects of the empire were treated with more indulgence than was shown to the pernicious, or at least the unpopular, commerce of Arabia and India. There is still extant a long but imperfect catalogue of eastern commodities, which about the time of Alexander Severus were subject to the payment of duties; cinnamon, myrrh, pepper, ginger, and the whole tribe of aromatics; a great variety of precious stones, among which the diamond was the most remarkable for its price, and the emerald for its beauty; Parthian and Babylonian leather, cottons, silks, both raw and manufactured, ebony ivory, and eunuchs. We may observe that the use and value of those effeminate slaves gradually rose with the decline of the empire. II. The excise, introduced by Augustus after the civil wars, was extremely moderate, but it was general. It seldom exceeded one per cent.; but it comprehended whatever was sold in the markets or by public auction, from the most considerable purchases of lands and houses, to those minute objects which can only derive a value from their infinite multitude and daily consumption. Such a tax, as it affects the body of the people, has ever been the occasion of clamor and discontent. An emperor well acquainted with the wants and resources of the state was obliged to declare, by a public edict, that the support of the army depended in a great measure on the produce of the excise.*