Chapter 3 considers the evolution of military disciplinary practices as military thought became ever more akin to a human science. It focusses on a key work in the theorisation of military discipline, Robert Jackson’s A Systematic View of the Formation, Discipline, and Economy of Armies (1804). Drawing on his extensive experience as a surgeon in the British army, Jackson places the medicalised body at the heart of military discipline. He insists that the soldier must be viewed as a living organism, possessed of a complex and self-governing interiority that determines how tactics operate. In Jackson’s conception, the soldier appears as a self-governing figure who functions independently and at a distance from disciplinary sites, a figure who more closely resembles the modern subject than the mechanical automatons associated with Frederick the Great’s military drill practices. More than this, however, Jackson’s book reveals how Romantic aesthetics penetrated military thought. The military’s concern with the imagination of the soldier in the field was undoubtedly a ‘shock’ to poets, Clausewitz surmised, but was nonetheless central to emergent aesthetic concerns with perception and interiority that suggest an unexplored context of wartime media surrounding a Romantic poetics and its formation of subjectivity.

The previous themes reach into modern debates about freedom and necessity, which are still central in education and psychology today. Contributing to the rise of formal disciplines of developmental and child psychology, educational psychology, clinical psychology and cognitive psychology, as well as psychiatry, empirical approaches based on sense perception began in the mid-eighteenth century; but they are equally the outcome of broader religious and cultural influences. The book therefore concludes with an overview of the direct traces on the modern disciplines of the religious ideas discussed in earlier chapters: in Britain through David Hartley, Joseph Priestley and Francis Galton, and the nature-versus-nurture formula; and in France Hippolyte Taine, Alfred Binet (creator of the ‘mental age’ score, subsequently IQ measurement) and Jean Piaget himself.