The fourth part of Thomas Hobbes’s Leviathan (1651) is labelled ‘The Kingdom of Darkness’. Following on from his discussion of human nature, civil sovereignty and the proper ‘Christian Commonwealth’, the title of the final part leads the reader to expect a section on Satan’s reign in hell. In fact, it is about the ecclesiastic class, with the Catholic Church coming in for particularly rough treatment. This ‘Confederacy of Deceivers … to obtain dominion over men in this present world, endeavor by dark, and erroneous Doctrines, to extinguish in them the Light, both of Nature, and of the Gospell; and so to dis-prepare them for the Kingdome of God to come’.

In Dmitri Levitin’s erudite and massive history of European thought in the 17th century, the ‘Confederacy of Deceivers’ who have led others into the wasteland of error consists not of priests but of philosophers. Levitin’s ‘Kingdom of Darkness’ is ruled by those early modern thinkers devoted to metaphysics, particularly those who supposed it to provide the necessary foundations for natural philosophy (physics, chemistry, medicine and other sciences). Metaphysics is about the ultimate natures of things and the most general principles that govern them. It involves determining what is ‘really real’, and thus what kinds of entities and processes one may invoke to explain phenomena. Metaphysics also concerns such matters as the nature of God, angels and the human soul.

For Levitin, the most egregious offender was Descartes. His four-part Principles of Philosophy (1644) begins with demonstrations of the existence of God and the distinction between thinking substance (mind or soul) and extended substance (material bodies), as well as an epistemological attempt to prove that attaining true knowledge is possible through the intellect. This is followed by a discussion of the universal principles of physical phenomena, framed in strictly mechanistic terms of the motion, rest and impact of minute particles of matter in a plenum, in which body is identical with geometric space and a vacuum is impossible.

‘Metaphysical physics’ was nothing new. It was essential to the various medieval and early modern versions of Aristotelian natural philosophy. What was new with Descartes and his colleagues was the rejection of opaque, even ‘occult’ forms of agency. Rather than explaining the falling of bodies by the inherence