 It should be noted, however, that Leibniz did think that there was a sense in which one could say that mental events influence bodily events and vice-versa. He wrote to Antoine Arnauld that although “one particular substance has no physical influence on another … nevertheless, one is quite right to say that my will is the cause of this movement of my arm …; for the one expresses distinctly what the other expresses more confusedly, and one must ascribe the action to the substance whose expression is more distinct” (28 November 1686 (draft); G II, 71/LA 87). In this passage, Leibniz sets forth what he takes the metaphysical reality of apparent inter-substantial causation to amount to. We begin with the thesis that every created substance perceives the entire universe, though only a portion of it is perceived distinctly, most of it being perceived unconsciously, and, hence, confusedly. Now consider two created substances, x and y (x not identical to y), where some state of x is said to be the cause of some state of y. Leibniz’s analysis is this: when the causal state of affairs occurred, the relevant perceptions of substance x became more distinct, while the relevant perceptions of substance y became more confused. Insofar as the relevant perceptions of x become increasingly distinct, it is “causally” active; insofar as the relevant perceptions of substance y become increasingly confused, it is passive. In general, causation is to be understood as an increase in distinctness on the part of the causally active substance and an increase in confusedness on the part of the passively affected substance. Again, each substance is programmed at creation to be active/passive at the relevant moment with no occurrence of real substantial interaction.