[1] In his Theory and History, Ludwig von Mises wrote on the relationship between praxeology and thymology: [Thymology] 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.
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.
It deals with the mental processes that result in a definite kind of behavior, with the reactions of the mind to the conditions of the individual's environment.
But the natural sciences must admit that this factor must be considered as real also from their point of view, as it is a link in a chain of events that result in changes in the sphere the description of which they consider as the specific field of their studies.