We will now begin a careful consideration of each several point, as far as they can be grasped and understood; for it has been wisely said, in my opinion, that it is a scholar's duty to study the real nature of anything before he formulates his belief about it.
Speculative Science may he divided into three kinds: Physics, Mathematics, and Theology. Physics deals with motion and is not abstract or separable (i.e. ); for it is concerned with the forms of bodies together with their constituent matter, which forms cannot be separated in reality from their bodies. As the bodies are in motion -- the earth, for instance, tending downwards, and fire tending upwards, form takes on the movement of the particular thing to which it is annexed.
Mathematics does not deal with motion and is not abstract, for it investigates forms of bodies apart from matter, and therefore apart from movement, which forms, however, being connected with matter cannot be really separated from bodies.
Theology does not deal with motion and is abstract and separable, for time Divine Substance is without either matter or motion. In Physics, then, we are bound to use scientific, in Mathematics, systematical, in Theology, intellectual concepts; and in Theology we will not let ourselves be diverted to play with imaginations, but will simply apprehend that Form which is pure form and no image, which is very Being and the source of Being For everything owes its being to Form. Thus a statue is not a statue on account of the brass which is its matter, but on account of the form whereby the likeness of a living thing is impressed upon it: the brass itself is not brass because of the earth which is its matter, but because of its form. Likewise earth is not earth by reason of unqualified matter, but by reason of dryness and weight, which are forms. So nothing is said to be because it has matter, but because it has a distinctive form. But the Divine Substance is Form without matter, and is therefore One, and is its own essence. But other things are not simply their own essences, for each thing has its being from the things of which it is composed, that is, from its parts. It is This and That, i.e. it is the totality of its parts in conjunction; it is not This or That taken apart. Earthly man, for instance, since he consists of soul and body, is soul and body, not soul or body, separately; therefore he is not his own essence. That on the other hand which does not consist of This and That, but only of This, is really its own essence, and is altogether beautiful and stable because it is not grounded in any alien element. Wherefore that is truly One in which is no number, in which nothing is present except its own essence. Nor can it become the substrate of anything, for it is pure Form, and pure Forms cannot be substrates. For if humanity, like other forms, is a substrate for accidents, it does not receive accidents through the fact that it exists, but through the fact that matter is subjected to it. Humanity appears indeed to appropriate the accident which in reality belongs to the matter underlying the conception Humanity. But Form which, is without matter cannot be a substrate, and cannot have its essence in matter, else it would not be form but a reflexion. For from those forms which are outside matter come the forms which are in matter and produce bodies. We misname the entities that reside in bodies when we call them forms; they are mere images; they only resemble those forms which are not incorporate in matter. In Him, then, is no difference, no plurality arising out of difference, no multiplicity arising out of accidents, and accordingly no number.