What do you mean different substantial principles?
A principle is
that from which a thing in any way proceeds. For example, the principles of any science are the definitions, axioms and postulates from which the entire science is built. Those are principles as regards knowledge. Substantial principles, on the other hand, are principles as regards reality, and they refer to those things
from which substances are derived or made up.
Aristotle distinguished two natural principles that enter into the constitution of every mobile or material substance:
prime matter and
substantial form.
To explain this I must first bring up his classic distinction between a
potential being (otherwise known as a “being–in–potency”) and an
actual being (or a “being–in–act”). A being is in potency, or is a potential being, inasmuch as it has the capacity to become or to be something; a being is in act, or is an actual being, inasmuch as it already is what it is. Putting it another way, a being is actually what it is; potentially, it is what it may become. For example, before paper burns into ashes, it is actually paper, but potentially it is ash.
Now “form” is the principle by which a substance is what it actually is; “matter” is the principle by which a substance is potentially what it may become. Every material substance is a composite of matter and form because every material substance actually exists as a determinate kind of being (due to its form), but it potentially exists as a different kind of being (due to its matter). Note that “matter” and “form” are
intrinsic principles that constitute a substance. They are not like the white paint on a piece of wood that is extrinsic to the substance of the wood itself. They are intrinsic to the substance and are called
substantial principles because together they constitute a material substance, although each one is not a complete substance in itself.
It should be evident now that the “matter” of the philosopher is not the same thing as the “matter” of the physicist. The “matter” of the philosopher is not something you can handle in the laboratory. No, it is not a reality that you can perceive by your senses, but a reality that is
understood (by the mind). It is the latent potency in every material substance that enables it to change into other kinds of substances.
The “matter” of the philosopher cannot exist apart from form. There is no such thing as pure matter existing in the world without form. For, nothing in the world exists indeterminately, without any formal determinations. This is why Aristotle found it necessary to call it
prime matter, to distinguish it from the material substance itself of which it is a part. Aristotle calls the fully constituted material substance “secondary matter.” The potency in a piece of wood is prime matter; the wood itself is secondary matter. Prime matter exists in the world, but it never exists alone without form. It only exists in secondary matter.
To be continued in my next post below.
