Map of xian for They advocated direct, rather than indirect taxation” in particular, a single tax on land”that would minimize the cost of collection. They maintained the position that a tax on industry merely taxed land in an indirect and therefore uneconomical way. However, the landowners resisted this argument, and ensuing discussions about the policy revealed some of the defects in the Tableau. The issue ultimately became one of the major factors in the decline of the physiocratic influence because Quesnay argued that competition would reduce the value of the product of the sterile class to its costs of production, but could not show why competition in agriculture would not also reduce its surplus to zero. It seems likely that the concept of the bon prix or good price for agricultural products was essential to maintaining the surplus product in agriculture, but it was not clear how it was to be sustained. Interpreting it as a legal minimum price would be a clear departure from the laissez-faire environment that they supported. Quesnay did not advocate an attack on the landed interest but it was possible to interpret his ideas that way. Map of xian 2016.