The second proof of God's existence, unity and incorporeality, that based upon the distinction between "possible" and "necessary" existent,[270] which has its origin in Alfarabi and Avicenna, is also found in Ibn Daud.[271] The other two proofs[272] are Maimonides's own, _i. e._, they are not found in the works of his Jewish predecessors. As in the exposition of the theory of the Mutakallimun Maimonides began with their fundamental principles, so here he lays down twenty-six propositions culled from the Physics and Metaphysics of Aristotle and his Arabian commentators, and applies them later to prove his points. He does not attempt to demonstrate them, expecting the reader to take them for granted, or to be familiar with them from a study of the philosophical sources. Ibn Daud presupposed less from his readers, having written as he said, for beginners; hence he proves many of the propositions which Maimonides lays down dogmatically. Possibly Maimonides expected his readers to be familiar with the work of his immediate Jewish predecessor. The twenty-six propositions of the philosophers are as follows: 1. There can be no infinite object possessing magnitude. 2. There cannot be an infinite number of bodies possessing magnitude, all at the same time. 3. There cannot be an infinite chain of cause and effect, even if these links are not possessed of magnitude, for example, intellects. 4. Change is found in four categories. In substance--genesis and decay. In quantity--growth and diminution. In quality--qualitative change. In place--motion of translation. 5. All motion is change, and is the realization of the potential. 6. Motion may be _per se_, _per accidens_, forcible, partial, the latter coming under _per accidens_. An example of motion _per se_ is the motion of a body from one place to the next; of motion _per accidens_, when the blackness of an object is said to move from one place to another. Forcible motion is that of the stone when it is forced upward. Partial motion is that of a nail of a ship when the ship moves. 7. Every changeable thing is divisible; hence every movable thing is divisible, _i. e._, every body is divisible. What is not divisible is not movable, and hence cannot be body. 8. That which is moved _per accidens_ is necessarily at rest because its motion is not in itself. Hence it cannot have that accidental motion forever. 9. A body moving another must itself be in motion at the same time. 10. Being in a body means one of two things: being in it as an accident, or as constituting the essence of the body, like a natural form. Both are corporeal powers. 11. Some things which are in a body are divided with the division of the body. They are then divided _per accidens_, like colors and other powers extending throughout the body. Some of the things which constitute the body are not divisible at all, like soul and intellect. 12. Every power which extends throughout a body is finite, because all body is finite.