White Collar by C. Wright Mills — Read

Most of the old professionals have long been free practitioners; most of the new ones have from their beginnings been salaried employees. But the old professions, such as medicine and law, have also been invaded by the managerial demiurge and surrounded by sub-professionals and assistants. The old practitioner's office is thus supplanted by the medical clinic and the law factory, while newer professions and skills, such as engineering and advertising, are directly involved in the new social organizations of salaried brain power.

Free professionals of the old middle class have not been so much replaced in the new society as surrounded and supplemented by the new groups. In fact, over the last two generations, free practitioners have remained a relatively constant proportion (about 1 per cent) of the labor force as a whole, and about 2 per cent of the middle class as a whole. In the meantime, however, salaried professionals have expanded from 1 to 6 per cent of all the people at work, and from about 4 to 14 per cent of the middle class. The expansion of the professional strata has definitely been an expansion of its new middle-class wing. Even in the old middle-class world of 1870, salaried professionals (mainly nurses and schoolteachers) made up a dominant section of the professional strata; only 35 per cent were free professionals. By 1940, however, only 16 per cent were.