The Wealth of Nations by Part 5 Chapter 1 Page 252

competition with them, in the same state with a merchant who attempts to trade without a bounty in competition with those who trade with a considerable one. If he sells his goods at nearly the same price, he cannot have the same profit, and at least, if not bankruptcy and ruin, will infallibly be his lot. If he attempts to sell them much dearer, he is likely to have so few customers that his circumstances will not be much mended. The privileges of graduation, besides, are in many countries necessary, or at least extremely convenient, to most men of learned professions, that is, to the far greater part of those who have occasion for a learned education.

But those privileges can be obtained only by attending the lectures of the public teachers. The most careful attendance upon the ablest instructions of any private teacher