 Taking substances as paradigmatic causes may help us to better appreciate Leibniz’s compatibilist account of freedom. Except for divine activity, all genuine causation takes place intrasubstantially—that is, within a substance. Substances are the causes of their future states and determine those effects. However, knowing that a substance’s future states flow with certainty from prior states due its own inherent powers does not automatically entail that all of its states are absolutely essential to it. That I must write this entry on Leibniz—given my initial states, it was certain or determined for me to write it—does not entail that it is part of my essence, my very identity, to write this entry. Leibniz wants to maintain that I could have acted otherwise. And thus I freely wrote it, even though it was certain that I did so. 