This work of six years of labor appeared in 1940. It was the predecessor to Human Action published nine years later. Epistemology and value theory were the two central problems.
Action includes more than behavior. Value is really preference. Choice matters more than need. The Law of Diminishing Marginal Utility has nothing to do with satiation. The line is drawn between praxeology and psychology.
Socialism is incapable of economic calculation. Political interventions in the money supply are unwarranted. Entrepreneur and entrepreneurship are distinguished. Begin reading Human Action with Part Four. Even when Mises restated previous concepts he revised them, so there was much that was new in this book.
Lecture 8 of 10 from The Life, Times, and Work of Ludwig von Mises, a George and Joele Eddy Seminar.