Physiological Introduction or Principles of the Human Body

For to become is to change, and to change is the transition of something—namely, primary matter the fundamental, undifferentiated substrate of physical reality—from non-being, which is indicated by privation the absence of a specific form, to the being of a substantial form the principle that gives an entity its specific nature. As for secondary parts, they are the union and the two instants of time, in the first of which the prior form is removed, and in the second, a new one is produced—that is, introduced. Thus, the primary parts of the whole "in fact," or the permanent whole, are matter and form, while the secondary part is the union, by means of which the form is joined to the matter. It is these parts of the permanent whole that we shall discuss in this point.

Suppose 3. that in order for the essence of a substantial composite to be properly understood, it must be known: 1. That a substance is a being in itself, whereas an accident is a being in another—that is, a being intended by nature for the sake of something else that is adequately distinct from itself. 2. That the substantial form is not the entire quiddity, or essence, of the substantial composite, but only a part, although it is a primary part, which, if understood under the quiddity, can be called the entire quiddity, or essence, of the substantial composite. 3. That the ultimate actuality, by which indifference the state of being unformed or common ought to be removed, consists in an indivisible, not in two really distinct predicates, since through these, either the indifference would not be removed,

or there would be two ultimate actualities, when one would suffice. Hence 4. there exists a mode, or modal entity, which is a pure relationship of the indifferent thing, purely lovable because of that to which it is united, so that, specifically, the indifference may be removed. Such modes are locations, actions, passions, unions, etc.

Suppose 4. The philosophical foundation, that nothing comes from nothing, and nothing can be reduced to nothing, is to be understood as meaning that by the power of a created agent, nothing is made from nothing—that is, no created agent has the power of creating, but acts in dependence upon a subject already created. Therefore, it is evident first that a created agent, or creature, or secondary cause, just as it always presupposes something for its own essence, by that very fact—since it is a created being—must also necessarily presuppose for its operation something that in reality is nothing other than primary matter. 2. That the Creator, or the first cause of all, just as it presupposes nothing before itself regarding its own essence, so it presupposes nothing, or at least ought not to be required to presuppose anything in its mode of operating. 3. That to create is to produce independently of matter,