 Occasionalism denies causation not only among finite substances, and so rules out any inflow between cause and effect, but also within finite substances. In other words, regarding finite substances, there is neither intersubstantial nor intrasubstantial causation. Taken individually or jointly, finite substances have no genuine causal efficacy. When the strings of Hendrix’s guitar vibrate, Hendrix is not the real cause of the vibration. Nor are his fingers, wrist, and arm real causes. Is the vibration then uncaused for the occasionalist? No, for there is God. God, thought by many of Leibniz’s contemporaries to be the only infinite substance, is considered to be the only real cause. God causes the strings on Hendrix’s guitar to vibrate on the occasion of Hendrix’s volition—itself caused by God—to strum the strings on his guitar. Al-Ghazali, Nicolas Malebranche, and Louis La Forge, among others, were occasionalists.