121] But this tax, or capitation, on the proprietors of land, would have suffered a rich and numerous class of free citizens to escape.

With the view of sharing that species of wealth which is derived from art or labor, and which exists in money or in merchandise, the emperors imposed a distinct and personal tribute on the trading part of their subjects.
[188] Some exemptions, very strictly confined both in time and place, were allowed to the proprietors who disposed of the produce of their own estates.

Some indulgence was granted to the profession of the liberal arts: but every other branch of commercial industry was affected by the severity of the law.

The honorable merchant of Alexandria, who imported the gems and spices of India for the use of the western world; the usurer, who derived from the interest of money a silent and ignominious profit; the ingenious manufacturer, the diligent mechanic, and even the most obscure retailer of a sequestered village, were obliged to admit the officers of the revenue into the partnership of their gain; and the sovereign of the Roman empire, who tolerated the profession, consented to share the infamous salary, of public prostitutes.

[188a] As this general tax upon industry was collected every fourth year, it was styled the Lustral Contribution: and the historian Zosimus [189] laments that the approach of the fatal period was announced by the tears and terrors of the citizens, who were often compelled by the impending scourge to embrace the most abhorred and unnatural methods of procuring the sum at which their property had been assessed.