 Avicenna considers this account of “cause” to apply to all instances of the causal relation. Still, he recognizes important differences across the various things which function as causes. Most important are the differences between God and sublunary substance. According to Avicenna, with God’s existence, the existence of his sole immediate effect, the first intelligence, is necessary. His reasoning involves the following ideas. First, God needs nothing outside himself to produce the first intelligence. Second, God is immutable. Avicenna considers God’s immutability to entail that his knowledge and volition are also immutable. God’s knowledge and volition are the principles by which he acts. So, whenever God exists, he possesses the knowledge and volition by which he produces the first intelligence. So, with God’s existence, the existence of the first intelligence is necessary.