According to traditional histories of European medicine, ideas of how blood circulates around the body changed radically in the first half of the seventeenth century, with the publication of William Harvey’s De Motu Cordis (1628). Historians of science, such as Thomas Henry Huxley (1878) and Thomas Wright (2012), argue that this publication brought about a new set of insights into the general circularity of the body’s resources, and a secularization of spirit, mind and bodily functions. However, a number of English vernacular texts predating Harvey’s magnum opus, including Nicholas Gyer’s The English Phlebotomy (1592), John Harward’s Phlebotomy (1601) and Helkiah Crooke’s Mikrokosmographia (1615), already developed a natural philosophy of blood, focusing on the circulation and balancing of sanguine spirits and passions, albeit this perspective on blood was not entirely divorced from theological notions.

This paper will argue that historians of science have overlooked the central congruity between secular and sacred perspectives on spirit and blood in early modern thought. In fact, practically all the canonical English authors on theories of blood and practices of blood letting were trained in theology as well as surgery or physic, and often practiced in both fields. As S. Manning Stevens (1997), Gail Kern Paster (2004) and Caroline Walker Bynum (2007) have shown, sacred and secular notions of spirit, passions and the humoural body share a common language in early modern English science, and ideas of circularity were widespread in medical as well as in theological conceptions of the body. Distributions of blood and spirit throughout the body could not be fully explained by either theology or natural philosophy alone, but required the presence of both perspectives.