() is what a man knows about the way in which people value different conditions, about their wishes and desires and their plans to realize these wishes and desires. It is the knowledge of the social environment in which a man lives and acts or, with historians, of a foreign milieu about which he has learned by studying special sources. Why one man chooses water and another man wine is a thymological (or, in traditional terminology, psychological) problem. But it is of no concern to praxeology and economics. The subject matter of praxeology and of that part of it which is so far best developed─economics─is action as such and not the motives that impel a man to aim at definite ends.