  Holbach’s account of matter may best be understood against the background of the Lockean account, which is more familiar and from which in large part it is developed. (Israel 2006 traces the sources of the views of Holbach and the coterie in detail.) On Locke’s account of bodies (Book 2, Chapter 8 of his Essay), all bodies possess “real” or “primary” qualities (solidity, extension, figure, number, and motion). Real qualities are those which are “inseparable” from the bodies themselves. To take Locke’s example (Essay 2.8.9), a grain of wheat will have solidity, extension, figure and so on when it is intact, and it will retain these properties whatever happens to it. Locke distinguishes primary qualities from powers in bodies to produce sensations in observers, which he calls secondary qualities. Secondary qualities, for example, are color, sound, taste, and so on. Because he hesitates to call secondary qualities real qualities, it is clear that Locke takes them to have a metaphysical status different from that he gives primary qualities.