It is widely believed that Darwin’s Galápagos finches inspired his theory of natural selection. Nothing could be further from the truth.  Darwin’s failure to label his Galápagos finch specimens by island, and his lack of useful behavioral observations about the differing diets of these birds, limited his ability to argue that their diverse beaks had evolved by natural selection to fill different ecological niches. For these reasons, these birds are not even mentioned in the Origin of Species. As is well established by historians of science, and as is further supported by Darwin’s own testimony, his revolutionary theory of natural selection was inspired by his reading of Thomas Robert Malthus’s book On Population in September 1838, three years after Darwin’s historic visit to the Galápagos Islands and two years after his return to England on the Beagle.  What Darwin’s Galápagos birds, including the famous finches, helped him to understand is that species often grade insensibly into one another and that varieties, as he later argued in the Origin of Species, are “incipient species.” It was the largely underappreciated existence of this variability among species in nature that allowed Darwin to grasp how natural selection might give rise to new species. Inspired in part by David Lack’s (1947) influential book Darwin’s Finches, the pervasive myth associated with these iconic birds is a classic instance of how important scientific discoveries often become telescoped around a dramatic moment of eureka-like insight, obscuring what typically proves to be a more protracted and conceptually multifaceted processes of scientific innovation.

Thomas Roberts Malthus is typically considered a ‘classical’ economist together with Adam Smith and David Ricardo. However, in important respects his view differed fundamentally from theirs, as Keynes emphasised in his biographical essay on Malthus. Most importantly, Malthus vehemently opposed Ricardo’s doctrine that it was impossible for effective aggregate demand to be deficient. Keynes, who also insisted on the possibility of effective demand failures, therefore considered Malthus to have been a precursor of his own view. The chapter discusses the following themes. What was the classical conception of ‘Say’s law’ and what were the reasons why Ricardo endorsed and Malthus rejected it? What were the main lines of reasoning in the ‘general glut’ controversy between Malthus and Ricardo? Was Keynes justified in considering Malthus’s doctrine to foreshadow his own doctrine, and if not, why not? What are the reasons why according to Pasinetti the classical (Ricardo-Sraffa) approach to the theory of relative prices and income distribution is compatible with Keynes’s principle of effective demand?

Potatoes were deeply embedded in nineteenth-century arguments about the merits of capitalism. The potato’s contested status emerges clearly in discussions about Ireland. In the eighteenth century, the potato’s contribution to the Irish diet had been viewed positively, because it enabled population growth. By the mid-nineteenth century it had become both an alarming illustration of the perils of economic autarky and a testament to the evils of capitalism. Commentators on all sides of the debate agreed that the potato encapsulated something of capitalism’s essence. At the same time, as urbanisation and industrialisation advanced, the conviction that the population’s eating habits had a material impact on the body politic only deepened. The new language of nutrition provided a vocabulary for expressing this relationship. From the mid-nineteenth century the potato’s growing importance within the working-class diet attracted the worried attention of nutritionists and statesmen, who condemned the effects of ‘lazy potato blood’ on the working body: the potato’s popularity with workers was blamed for lacklustre economic growth. Talking about potatoes provided a way for working people, scientists, economists and politicians to discuss the enormous changes that were reshaping nineteenth-century Europe in ways that stressed the close connections between economic practices and everyday eating habits.