  Al-Kindi’s most significant work, On First Philosophy (for which see Abu Rida 1950, 97–162, Ivry 1974, Rashed and Jolivet 1998, 9–99), is devoted to “first philosophy” or metaphysics, a science al-Kindi immediately identifies with the study of God. Since all philosophy is an inquiry into truth, first philosophy is the knowledge of God, who is “the first truth and the cause of all truth.” While this may not sound like it has much to do with Aristotle’s understanding of first philosophy as the science of being, al-Kindi closely associates being with truth (“everything that has being has truth”). For him, to say that God is the cause of all truth is tantamount to saying that God is the cause of all being, a point made more explicit at the end of what remains to us of On First Philosophy (see further below, 3.2).