Carl Menger: "All things are subject to the law of cause and effect. This great principle knows no exception."
Investigations into the Method of the Social Sciences The world of phenomena can be considered from two essentially different points of view. Either there are concrete phenomena in their position in space and tinle and in their concrete relationships to one another, or else there are the empirical forms recurring in the variation of these, the knowledge of which forms the object of our scientific interest. The one orientation of research is aimed at cognition of the concrete, or more correctly, of the individual aspect of phenomena; the other is aimed at cognition of their general aspect. Thus, corresponding to these two main orientations of the striving for cognition, two great classes of scientific knowledge confront us, the first of which we will in short call individual, the latter general.
On the Origins of Money There is a phenomenon which has from of old and in a peculiar degree attracted the attention of social philosophers and practical economists, the fact of certain commodities (these being in advanced civilizations coined pieces of gold and silver, together subsequently with documents representing those coins) becoming universally acceptable media of exchange. It is obvious even to the most ordinary intelligence, that a commodity should be given up by its owner in exchange for another more useful to him. But that every economic unit in a nation should be ready to exchange his goods for little metal disks apparently useless as such, or for documents representing the latter, is a procedure so opposed to the ordinary course of things, that we cannot well wonder if even a distinguished thinker like Savigny finds it downright "mysterious."
Principles of Economics All things are subject to the law of cause and effect. This great principle knows no exception, and we would search in vain in the realm of experience for an example to the contrary. Human progress has no tendency to cast it in doubt, but rather the effect of confirming it and of always further widening knowledge of the scope of its validity. Its continued and growing recognition is therefore closely linked to human progress.