Commentaria in Primam Partem Summae Theologiae

In the title, one in number. — In the body, four. First, the diverse opinions on the question at issue are set forth.

Second, the way of examining which opinion is truer is set forth: and it is said that one must proceed from the cause of the unity of time. And it is proved: because we arrive at knowledge of spiritual things through corporeal things.

Third, he enters upon the way itself. Here four opinions concerning the cause of the unity of time are brought forward: the first, from the unity of number; the second, from the unity of a principle, namely eternity; the third, from the unity of the first subject, namely prime matter; the fourth, from the unity of the first motion. — And the first is indeed rejected as follows. Time is not number absolutely, but a numbered thing, namely in continuous motion: therefore it is not one from the unity of number but one in number. — The second and third, however, are rejected together, as follows. Time is one simply: therefore it is not one only by a remote principle and subject. The inference holds: because things one in subject or principle are one only in a qualified sense. — The fourth, however, is proved as follows. The first motion is the most simple: therefore it is the measure of the others: therefore it is related to time not only as the measured to the measure, but as the subject to the accident: therefore from its unity time is one. The first consequence is proved from Book X of the Metaphysics. The others, however, are left as self-evident: since it is established that the quantity of the first measured thing is the measure conjoined to it, but of the others separate; and for this reason it is not multiplied with the multiplication of the others, but only of the first; just as universally an accident is multiplied with the multiplication of its subject. Therefore, since the first is not multiplied, neither is the measure; as in the case at hand.

Fourth, he principally derives from that assigned route a response to the question, positing two conclusions according to the two opinions about the angels. The first is: there are many aeons. It is proved. The first things of the aeviternal order are many; therefore. The second is: the aeon is one only. It is proved. The first thing of the aeviternal order is one only; therefore. — The antecedents are those very diverse opinions. The inferences are grounded on the treatment made concerning the unity of time, whose root was: a measure is multiplied by the multiplication of what is first measured by it. — And since from these no certain answer to the question is obtained, therefore he adds that the second conclusion must be held, because the opinion supporting it is more probable, as will be clear below. And thus the responsive conclusion is: The aeon is one only.

II. Note here that, just as every motion has its own prior and posterior within itself, so too it has its own numbered number of those, and consequently its own time. But since the number of any motion whatsoever is not by its nature certifying of all motions, but only the number of the first motion, on account of its greatest simplicity; therefore only the number of the first motion has the complete account of time. And for this reason time is one in number formally and taken completely: and there are many times as it were materially, or incompletely. And the same judgment holds concerning the aevum: for in the same way it is one and many. - Whether, however, the aevum is an accident, or the being (esse), or the essence of the aeviternal thing, must be inquired into in a special question: for this belongs to the business of metaphysics.

III. Concerning the things defined here, there are several doubts. First, Scotus, in the Second Book, distinction II, question III, censured the fact that the first aeviternal being is measured by the aevum (although it is itself the first, and the extrinsic measure of the others), on one ground. A measure is, by the nature of the thing, better known than what is measured: but nothing in the first aeviternal being is better known than its aeviternal substance: therefore nothing in it has the character of a measure of that substance. - Durandus, however¹ censured the extrinsic measurement of one aeviternal being by another, in three ways. First thus. That whose duration is more certain from its own definition than from comparison with something extrinsic is not measured in its duration by anything extrinsic. But an aeviternal being is of this kind. It is proved: because its proper definition is to be immutable according to nature. Second, infinite duration is not measurable: therefore. Third, not as much is not measurable: therefore. The inference holds: because the aevum lacks succession. - These and several other objections are recounted by Capreolus, in the Second Book, dist. II²; yet we shall deliberately pass over the rest, and say whence all of them will be resolved.

IV. For the clarification of this, then, know that, as may already be evident from what has been said³, the aeviternal is not measured by the aevum, whether intrinsically or extrinsically, in the manner of a continuous or successive or even discrete quantity, but in the manner of a unity: for the aevum is indivisible, whole at once, etc. For since the aevum is an immutable unity conjoined to mutability, the less any immutable thing is conjoined to mutability, the more immutable it is and the less composite, and thereby simpler, and consequently more one. We now suppose, moreover, that the aeviternal, the lower it is, the more closely it is conjoined to plurality: whence it also has less universal species, and operations that encompass fewer places or bodies. And therefore the supreme aeviternal, as the most immutable among immutable things thus (that is, joined to mutation), is most one: and consequently by its nature it possesses that whereby the other aeviternals, as such, are measured extrinsically through approach to and withdrawal from it.

V. Against Scotus⁴ therefore, the minor premise is denied. For I say that the aevum, existing in the first aeviternal being—whether it is its substance or its existence, or not—is better known in the respect of measure than the substance of the aeviternal being itself, as immutable. Since the aevum is nothing other than the unity, by way of measure, of such immutability: and hence the aevum itself is formally a unity, to which the reason of measure is primarily owed, as is clear from V⁵ and X Metaphysics.⁶ But a substance so immutable is one denominatively; and this denomination is expressed by the term aeviternal. It is universally evident, moreover, that what is formally such is more certain and better known by nature than what is such only denominatively. Therefore, although the substance of an angel is simply the best known among all things in it, nevertheless the aevum, in the genus or respect of measure, is better known than that substance: just as, although corporeal substance is better known in itself than quantity, yet in the genus of measure quantity is better known in itself.

VI. But to Durandus⁷ one must reply by denying the major premise, as is clear in quidditative perfection and measure. For quidditative perfection is better known from within than from without; and yet each quiddity is measured by the first quiddity of its genus. The sophism is therefore taking what is not a cause as a cause. For the cause of extrinsic measure's being more certain from outside than inside is not that, but rather the dependence of intrinsic certainty upon the extrinsic, as upon something simpler, as was said⁸. - To the second and third objections it is likewise said that they have no force against the measurable considered under unity. For the infinite and the non-quantum do not escape the ratio of uniformity.

There still remains the question of what that first aeviternal thing may be; but since it would be incidental to our present purpose, it will be treated in the tractate on the Angels⁹.