distinct. Now equality implies both--namely,
distinction of persons, for nothing can be said to be equal to
itself; and unity of essence, since for this reason are the persons
equal to one another, that they are of the same greatness and
essence. Now it is clear that the relation of a thing to itself is
not a real relation. Nor, again, is one relation referred to another
by a further relation: for when we say that paternity is opposed to
filiation, opposition is not a relation mediating between paternity
and filiation. For in both these cases relation would be multiplied
indefinitely. Therefore equality and likeness in the divine persons
is not a real relation distinct from the personal relations: but in
its concept it includes both the relations which distinguish the
persons, and the unity of essence. For this reason the Master says
(Sent. i, D, xxxi) that in these "it is only the terms that are
relative."
_______________________

SECOND ARTICLE [I, Q. 42, Art. 2]

Whether the Person Proceeding Is Co-eternal with His Principle, As
the Son with the Father?

Objection 1: It would seem that the person proceeding is not
co-eternal with His principle, as the Son with the Father. For Arius
gives twelve modes of generation. The first mode is like the issue of
a line from a point; wherein is wanting equality of simplicity. The
second is like the emission of rays from the sun; wherein is absent
equality of nature. The third is like the mark or impression made by a
seal; wherein is wanting consubstantiality and executive power. The
fourth is the infusion of a good will from God; wherein also
consubstantiality is wanting. The fifth is the emanation of an
accident from its subject; but the accident has no subsistence. The
sixth is the abstraction of a species from matter, as sense receives
the species from the sensible object; wherein is wanting equality of
spiritual simplicity. The seventh is the exciting of the will by
knowledge, which excitation is merely temporal. The eighth is
transformation, as an image is made of brass; which transformation is
material. The ninth is motion from a mover; and here again we have
effect and cause. The tenth is the taking of species from genera; but
this mode has no place in God, for the Father is not predicated of the
Son as the genus of a species. The eleventh is the realization of an
idea [ideatio], as an external coffer arises from the one in the mind.
The twelfth is birth, as a man is