 Let’s now explain the presence of formal causation in perception. Some thinkers contemporaneous with Leibniz, most notably Pierre Bayle, found the apparent lack of continuity among our perceptions to be deeply problematic. We are often genuinely surprised by the content of our perceptions, some of which seem utterly disconnected from and radically unlike prior perceptions. But, given the Law of Continuity, Leibniz cannot allow perceptions to arise in a monad that are radically unlike preceding perceptions. To solve this problem, Leibniz offers his theory of petites or unconscious perceptions and says that this apparent lack of continuity in the actions of the individual substance results from our overlooking the complex multitude of unconscious perceptions, which flow, at every moment, from the individual’s nature. But the doctrine of petite perceptions alone is not sufficient to ground continuity. Rather, it is the rational relation among perceptions that serves to guarantee continuity in perceptual content. Leibniz speaks of the “marks [les marques]” that each perception of a substance contains for all other perceptions that substance will ever have (Discourse on Metaphysics §8). I take it that this relation among perceptions points to perceptions being formal causes; that is to say, a substance’s present states specify fully the content of its future states.