Psychologist Harry Helson (1898–1977) developed Adaptation-Level (AL) theory during the 1930s to the 1970s, while economics was being refined through ordinalism and expected utility theory. This essay accounts for the process of transmission of AL theory from psychophysics to behavioral psychology and eventually economics. It explains how the concept of adaptation reflectance, originally intended to explain color vision, developed into an experimental approach that caught the attention of both psychologists and economists working on welfare analysis and behavioral research. It also argues that the history of AL theory—so far, absent from narratives about economics and psychology—is worth exploring in order to gain a better understanding of the relationship between the two disciplines.

The article discusses François Quesnay’s dynamics of capital accumulation. First, we analyze the notion of bon prix to highlight the central analytical role played by profits in Quesnay’s growth dynamics. This leads us to challenge Ronald Meek’s interpretation ([1962] 2003) and to (re)propose Peter Groenewegen’s suggestion (1974 and 1983) that profits are not included in the net product for policy reasons. We also show that profits display features resembling a stable income component such as supervision wages (see Marx [1863] 1963). Second, we contest Steven Pressman’s argument (1994, pp. 143–154) that Quesnay missed the distinction between nominal and real variables by modeling how the farmers’ monetary interest (and profit) initiates the capital accumulation process (see Vaggi 1985), which over time leads to an increase of the (physical) surplus rate and thus of the net product in real terms.

In this paper we examine the criticism that Knut Wicksell advanced against Léon Walras’s treatment of capital and interest at the end of the nineteenth century, as well as the views of two distinguished followers of Walras concerning the points raised by the Swedish economist. As regards the first aspect, it should be noted that the criticism put forward by Wicksell at that time refers to the earlier editions of the Éléments, in which circulating capital is excluded from the analysis. We thus endeavor to clarify Wicksell’s remarks on the consequences of that exclusion for both the representation of the social production process and the determination of the interest rate. As to the second aspect, our discussion indicates that the appropriate way of treating the capitalistic element of production was an unsettled issue within the small circle of Walras’s followers at the end of the nineteenth century.

Analogies with rational mechanics played a pivotal role in the search for formal models in economics. In the period between the two world wars, a small group of mathematical economists tried to extend this view from statics to dynamics. The main result was the extensive application of calculus of variations to obtain a dynamic representation of economic variables. This approach began with the contributions put forward by Griffith C. Evans, a mathematician who, in the first phase of his scientific career, published widely in economics. Evans’s research was further developed by his student Charles Roos. At the international level, this dynamic approach found its main followers in Italy, within the Paretian tradition. During the 1930s, Luigi Amoroso, the leading exponent of the Paretian School, made major contributions, along with his student Giulio La Volpe, that anticipated the concept of temporary equilibrium. The analysis of the application of the calculus of variations to economic dynamics in the interwar period raises a set of questions on the application of mathematics designed to study mechanics and physics to economics.

Austrian capital theory tried to capture the intuitive and basically undeniable importance that time plays in economic life, but arguably was diverted down a blind alley with Eugen von Böhm-Bawerk’s average period of production, a purely physical measure of ‘roundaboutness’—the length of the production process. For the general case, such a measure is a chimera. But the intuition is strong, and the idea survived and reappeared at various points in the history of capital theory. Almost unknown to economists, an alternative value measure of roundaboutness has existed at least since John Hicks’s formulation of his average period (AP) in 1939, which, coincidentally, was exactly the same measure discovered by the financial actuary Frederick Macaulay in 1938, called by him “Duration” (D). Macaulay’s D, more richly interpreted as Hicks’s AP, is a measure that more appropriately captures what it was that the Austrians struggled to express over many years in their capital theory and in their analysis of the business cycle.

More than England and other states, the German principalities were, in the pre-industrial period, hampered by silver outflow and persistent pressures on the balance of payments, which led to idiosyncratic models and strategies of economic development usually but not entirely helpfully called “Cameralism.” It is less well understood how Cameralism, as a policy of order and development, and monetary theory went together. The present paper will sketch these working mechanisms as well as provide a few angles for new perspectives and future research. A first section after the brief introduction studies general issues of development in relation to balance-of-payment constraints (II), followed by the discourses on whether the domestic currency ought to remain stable in terms of intrinsic (silver) value (III), or whether it may be debased so as to raise domestic exports and competitiveness (IV). Both options were considered, at times and by varying actors, as valid strategies of promoting economic development, especially export-led growth, although most contemporaries viewed coin debasement as harmful to the economy. A fifth section discusses an alternative to the aforementioned strategies, that of raising effective monetary mass through increasing velocity. Since the Middle Ages and into the nineteenth century, the German economic tradition had a clear understanding of how velocity could be managed and the common weal stimulated by an increase in “vivacity” of circulation (V). In hindsight, it appears that we find here a powerful program towards promoting economic development and Europe’s rise towards capitalism. A conclusion will offer some thoughts for further research (VI).