Guide for the Perplexed, by Moses Maimonides, Friedländer tr. , at sacred-texts.com
THERE is a great difference between the knowledge which the producer of a thing possesses concerning it, and the knowledge which other persons possess concerning the same thing. Suppose a thing is produced in accordance with the knowledge of the producer, the producer was then guided by his knowledge in the act of producing the thing. Other people, however, who examine this work and acquire a knowledge of the whole of it, depend for that knowledge on the work itself. E.g., An artisan makes a box in which weights move with the running of the water, and thus indicate how many hours have passed of the day and of the night. The whole quantity of the water that is to run out, the different ways in which it runs, every thread that is drawn, and every little ball that descends--all this is fully perceived by him who makes the clock; and his knowledge is not the result of observing the movements as they are actually going on; but, on the contrary, the movements are produced in accordance with his knowledge. But another person who looks at that instrument will receive fresh knowledge at every movement he perceives; the longer he looks on, the more knowledge does he acquire; he will gradually increase his knowledge till he fully understands the machinery. If an infinite number of movements were assumed for this instrument, he would never be able to complete his knowledge. Besides, he cannot know any of the movements before they take place, since he only knows them from their actual occurrence. The same is the case with every object, and its relation to our knowledge and God's knowledge of it. Whatever we know of the things is derived from observation: on that account it is impossible for us to know that which will take place in future, or that which is infinite.
Our knowledge is acquired and increased in proportion to the things known by us. This is not the case with God. His knowledge of things is not derived from the things themselves: if this were the case, there would be change and plurality in His knowledge; on the contrary, the things are in accordance with His eternal knowledge, which has established their actual properties, and made part of them purely spiritual, another part material and constant as regards its individual members, a third part material and changeable as regards the individual beings according to eternal and constant laws. Plurality, acquisition, and change in His knowledge is therefore impossible. He fully knows His unchangeable essence, and has thus a knowledge of all that results from any of His acts. If we were to try to understand in what manner this is done, it would be the same as if we tried to be the same as God, and to make our knowledge identical with His knowledge. Those who seek the truth, and admit what is true, must believe that nothing is hidden from God; that everything is revealed to His knowledge, which is identical with His essence; that this kind of knowledge cannot be comprehended by us; for if we knew its method, we would possess that intellect by which such
knowledge could be acquired. Such intellect does not exist except in God, and is at the same time His essence. Note this well, for I think that this is an excellent idea, and leads to correct views: no error will be found in it; no dialectical argument; it does not lead to any absurd conclusion, nor to ascribing any defect to God. These sublime and profound themes admit of no proof whatever, neither according to our opinion who believe in the teaching of Scripture, nor according to the philosophers who disagree and are much divided on this question. In all questions that cannot be demonstrated, we must adopt the method which we have adopted in this question about God's Omniscience. Note it.