 In 1692, Malebranche published a short study, the Lois de la communication des mouvements (Laws of the Communication of Motions), in which he endorsed Descartes’s law of the conservation of the quantity of motion but offered rules governing collision that, unlike Descartes’s own rules, involve no appeal to a force in bodies to remain at rest. In correspondence with Malebranche, Gottfried Wilhelm Leibniz (1646–1716) emphasized difficulties with Descartes’s conservation law, and that correspondence led Malebranche to insert into a 1700 edition of the Lois the admission that experience reveals that such a law does not hold.