The Wealth of Nations by Part 5 Chapter 1 Page 281

In the Church of Rome, the industry and zeal of the inferior clergy are kept more alive by the powerful motive of self-interest than perhaps in any established Protestant church. The parochial clergy derive, many of them, a very considerable part of their subsistence from the voluntary oblations of the people; a source of revenue which confession gives them many opportunities of improving.

The mendicant orders derive their whole subsistence from such oblations. It is with them as with the hussars and light infantry of some armies; no plunder, no pay. The parochial clergy are like those teachers whose reward depends partly upon their salary, and partly upon the fees or honoraries which they get from their pupils, and these must always depend more or less upon their industry and reputation. The mendicant orders are like