The Wealth of Nations by Part 5 Chapter 1 Page 253

cannot always give any title to demand them. It is from these different causes that the private teacher of any of the sciences which are commonly taught in universities is in modern times generally considered as in the very lowest order of men of letters. A man of real abilities can scarce find out a more humiliating or a more unprofitable employment to turn them to. The endowment of schools and colleges have, in this manner, not only corrupted the diligence of public teachers, but have rendered it almost impossible to have any good private ones.

Were there no public institutions for education, no system, no science would be taught for which there was not some demand, or which the circumstances of the times did not render it either necessary, or convenient, or at least fashionable, to learn.