This edited volume explores the intersection of medicine and philosophy throughout history, calling attention to the role of quantification in understanding the medical body. Retracing current trends and debates to examine the quantification of the body throughout the early modern, modern and early contemporary age, the authors contextualise important issues of both medical and philosophical significance, with chapters focusing on the quantification of temperaments and fluids, complexions, functions of the living body, embryology, and the impact of quantified reasoning on the concepts of health and illness. With insights spanning from the sixteenth century to the nineteenth century, this book provides a wide-ranging overview of attempts to ‘quantify’ the human body at various points. Arguing that medicine and philosophy have been constantly in dialogue with each other, the authors discuss how this provided a strategic opportunity both for medical thought and philosophy to refine and further develop. Given today’s fascination with the quantification of the body, represented by the growing profusion of self-tracking devices logging one’s sleep, diet or mood, this collection offers an important and timely contribution to an emerging and interdisciplinary field of study.