is above all things, we should understand what is said of God,
not according to the mode of the lowest creatures, namely bodies, but
from the similitude of the highest creatures, the intellectual
substances; while even the similitudes derived from these fall short
in the representation of divine objects. Procession, therefore, is not
to be understood from what it is in bodies, either according to local
movement or by way of a cause proceeding forth to its exterior effect,
as, for instance, like heat from the agent to the thing made hot.
Rather it is to be understood by way of an intelligible emanation, for
example, of the intelligible word which proceeds from the speaker, yet
remains in him. In that sense the Catholic Faith understands
procession as existing in God.

Reply Obj. 1: This objection comes from the idea of procession in the
sense of local motion, or of an action tending to external matter, or
to an exterior effect; which kind of procession does not exist in
God, as we have explained.

Reply Obj. 2: Whatever proceeds by way of outward procession is
necessarily distinct from the source whence it proceeds, whereas,
whatever proceeds within by an intelligible procession is not
necessarily distinct; indeed, the more perfectly it proceeds, the
more closely it is one with the source whence it proceeds. For it is
clear that the more a thing is understood, the more closely is the
intellectual conception joined and united to the intelligent agent;
since the intellect by the very act of understanding is made one with
the object understood. Thus, as the divine intelligence is the very
supreme perfection of God (Q. 14, A. 2), the divine Word is of
necessity perfectly one with the source whence He proceeds, without
any kind of diversity.

Reply Obj. 3: To proceed from a principle, so as to be something
outside and distinct from that principle, is irreconcilable with the
idea of a first principle; whereas an intimate and uniform procession
by way of an intelligible act is included in the idea of a first
principle. For when we call the builder the principle of the house,
in the idea of such a principle is included that of his art; and it
would be included in the idea of the first principle were the builder
the first principle of the house. God, Who is the first principle of
all things, may be compared to things created as the architect is to
things designed.
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SECOND ARTICLE [I, Q. 27, Art. 2]