Guide for the Perplexed, by Moses Maimonides, Friedländer tr. [1904], at sacred-texts.com
ON attributes; remarks more recondite than the preceding. It is known that existence is an accident appertaining to all things, and therefore an element superadded to their essence. This must evidently be the case as regards everything the existence of which is due to some cause: its existence is an element superadded to its essence. But as regards a being whose existence is not due to any cause--God alone is that being, for His existence, as we have said, is absolute--existence and essence are perfectly identical; He is not a substance to which existence is joined as an accident, as an additional element. His existence is always absolute, and has never been a new element or an accident in Him. Consequently God exists without possessing the attribute of existence. Similarly He lives, without possessing the attribute of life; knows, without possessing the attribute of knowledge; is omnipotent without possessing the attribute of omnipotence; is wise, without possessing the attribute of wisdom: all this reduces itself to one and the same entity; there is no plurality in Him, as will be shown. It is further necessary to consider that unity and plurality are accidents supervening to an object according as it consists of many elements or of one. This is fully explained in the book called Metaphysics. In the same way as number is not the substance of the things numbered, so is unity not the substance of the thing which has the attribute of unity, for unity and plurality are accidents belonging to the category of discrete quantity, and supervening to such objects as are capable of receiving them.
To that being, however, which has truly simple, absolute existence, and in which composition is inconceivable, the accident of unity is as inadmissible as the accident of plurality; that is to say, God's unity is not an element superadded, but He is One without possessing the attribute of unity. The investigation of this subject, which is almost too subtle for our understanding, must not be based on current expressions employed in describing it, for these
are the great source of error. It would be extremely difficult for us to find, in any language whatsoever, words adequate to this subject, and we can only employ inadequate language. In our endeavour to show that God does not include a plurality, we can only say "He is one," although "one" and "many" are both terms which serve to distinguish quantity. We therefore make the subject clearer, and show to the understanding the way of truth by saying He is one but does not possess the attribute of unity.
The same is the case when we say God is the First (Kadmon), to express that He has not been created; the term "First" is decidedly inaccurate, for it can in its true sense only be applied to a being that is subject to the relation of time; the latter, however, is an accident to motion which again is connected with a body. Besides the attribute "first" is a relative term, being in regard to time the same as the terms "long" and "short" are in regard to a line. Both expressions, "first" and "created," are equally inadmissible in reference to any being to which the attribute of time is not applicable, just as we do not say "crooked" or "straight" in reference to taste, "salted" or "insipid" in reference to the voice. These subjects are not unknown to those who have accustomed themselves to seek a true understanding of the things, and to establish their properties in accordance with the abstract notions which the mind has formed of them, and who are I not misled by the inaccuracy of the words employed. All attributes, such as "the First," "the Last," occurring in the Scriptures in reference to God, are as metaphorical as the expressions "ear" and "eye." They simply signify that God is not subject to any change or innovation whatever; they do not imply that God can be described by time, or that there is any comparison between Him and any other being as regards time, and that He is called on that account "the first" and "the last." In short, all similar expressions are borrowed from the language commonly used among the people. In the same way we use "One" in reference to God, to express that there is nothing similar to Him, but we do not mean to say that an attribute of unity is added to His essence.