He is known as the author of Political Economy from the Standpoint of the Historical Method, one of the 19th century methodological treatises on German historical school of economics. He taught at the University of Heidelberg for over 30 years and was maybe the most theoretically oriented economist of the older historical school.
Like others in the German Historical School, Knies disliked the attitudes of the 'classical school' (Adam Smith, David Ricardo and their followers), particularly their belief that the pursuit of individual self-interest redounded to the good of the community. In his 'Political Economy' (Braunschweig, 1853) he comments on page 157 that self-interest is 'in the public interest, so to speak, in its weakness and dangerous in its strength' (gemeinnützig, so zu sagen, in seine Schwäche und gefährlich in seine Stärke).
Some of his works are:
Political Economy from the Standpoint of the Historical Method, (1. ed., 1853, 2. ed., 1883)