The Monadology (La Monadologie, 1714) is one of Gottfried Leibniz’s best known works representing his later philosophy. It is a short text which sketches in some 90 paragraphs a metaphysics of simple substances, or monads. What he proposed can be seen as a modification of occasionalism developed by latter-day Cartesians. Leibniz surmised that there are indefinitely many substances individually ‘programmed’ to act in a predetermined way, each program being coordinated with all the others. This is the pre-established harmony which solved the mind body problem at the cost of declaring any interaction between substances a mere appearance, something which Leibniz accepted...