Materialism is the doctrine which finds the ultimate solution of all phenomena, physical and psychic, in the nature and
activity of universal matter or force.17
Matter, according to common signification, is the same as extended body. In modern use, matter is the opposite of either
form or spirit.18
Matter, in the technical definition of Aristotle and the Neo-Scholastics, denotes the potential element in being, potential
and indeterminate, and in opposition to "form" which represents the element of determination and actualization. Note that
the potency we treat here is not merely the possibility (potentia obiectiva) but is real potency (potentia subiectiva)
and this potency penetrates to the very nature of being, whether in the genus of substance or accident.19
Form is the element of determination and actualization. Real chance exists, both substantial (e.g., evoution of species)
and accidental. These changes demand new forms. These forms are not being in the strict sense (ens quod) but only the
principle "by which" (ens quo) being (ens quod).
Eduction is the way in which the form arises from the potency of the material. It would be mistaken to think that the active
form somehow comes for the outside to activate the potency of the matter. Form is "educed" from the potency of the material;
eduction is the opposite of induction. The definition of eduction is that form arises in the composite which comes from the
pre-existing material, without the form becoming and the form would then be introduced (into the composite).20
It is noteworthy that the human soul is not educed from the material, but is created; all other forms depend in their existence
on the material, i.e., they need its support; so also all other forms depend on the material in becoming, in so far as the
material also concurs in their production as a sustaining subject. This is the reason why forms are not only "in" (not induction
alone) matter, but become "from" matter (educed from the potency of the material).21
Principle is philosophically defined as that from which something proceeds in any way.22 Every cause is a principle,
because it gives being by an internal process to the thing caused.23 Not every principle is a cause, but can be
a condition or circumstance. Principle by definition is wider than cause.
Principle can be divided into the "principle which" (principium quod) defined as what truly and properly is said
to operate, like the soul; or principle can be the "principle by which" (principium quo) defined as what can either
be a substantial constituent of the nature which is operating, like prime matter and substantial form, or can be only an accidental
power by which something operates, like the will. The distinction is an important one, because in ordinary speech, and sometimes
even in scientific description, an elliptical and brief method of presentation is used, saying, the intellect thinks or the
will chooses. Properly speaking it is only the substantial soul, the supposit, which thinks with the intellect or desires
with the will.
Cause is a principle essentially influencing being in another.24 Causes are also defined as all those things
from which the known thing is, becomes, or is known.25 In the physical order, Aristotle teaches the efficient cause
produces the thing; the final cause is the reason for the production; the material cause is that from which the thing is produced
or constituted; and the formal cause, which the material determines to a certain type of being or action, is one with the
material in the intrinsic constitution of the thing. In the metaphysical order, cause is the intimate essence of the thing
conceived as the root of its properties.
Nature, a term with many meanings, is used here in the physical sense, namely, the quiddity (what it is), or the essence
of the thing. Nature is called quiddity in order to define what the thing is; essence by its order to being;
and nature by its order to operations of which it is the principle and cause. Aristotle defines nature as: "The principle
and cause of its motion and quiet in which it is first and essentially and not on the level of accident" (Aristotle Physics
2. 1. 192 a 40).26 Therefore, nature truly influences motion (motus), and the conservation of the mover
or the preservation in motion (quies); and the definition excludes habits, potencies, and accidents, which are the
instruments by which natural agents operate.
Vital Principle is the internal principle of life which is the substantial constitutive element of the nature or substance
of the living body, or as accidental powers of the substantial nature itself.27 In the first case, this intrinsic
principle of life (the soul) is called "ultimate," because nothing further need be sought in the living substance. In the
second case (accidental powers), the principle is called the "proximate" principle of vital operation, by which living nature
operates vitally.
Soul is the ultimate intrinsic principle of life, and can be defined as "the first (i.e., substantial or formal) act of
a physical, organized body which has the potency of life."28 Although the soul is substantial, it is not a complete
substance (ens quod) but an incomplete substance (ens quo). In the terminology of Aristotle, the actuating and
specifying principle of material substance is called "substantial form." The potential and restrictive principle is called
"first matter" or "prime matter." Klubertanz notes that the substantial form of an inanimate thing has no special name, but
the substantial form of a living thing is called "soul." The soul is not the efficient cause of the body, the parents are.
The soul is not even the efficient cause of the operations of a living thing, the supposit (the whole thing) is the efficient
cause.
Accident, philosophically, is defined as a being (ens) whose quiddity must be in another as in the subject of inhesion,
e.g., white in a man.29
Substance, philosophically, is defined as being (ens) whose quiddity must not be in another.30
Supposit is a substantial unity. Even in Latin, in texts such as Hoenen, the classical word "supposit" is replaced by the
more modern term "composite." Composite or supposit is a being with a complete nature subsisting in itself, with its own proper
act of existing.31 The concept is very important because all operations of inorganic things, plants and beasts
are the operations of the composite or supposit.32
Person is a supposit which has a rational nature.33
