Summa Theologica, Part I (Prima Pars) From the Complete...

Objection 1: It would seem that there is neither an evening nor a morning knowledge in the angels; because evening and morning have an admixture of darkness. But there is no darkness in the knowledge of an angel; since there is no error nor falsehood. Therefore the angelic knowledge ought not to be termed morning and evening knowledge.

Obj. 2: Further, between evening and morning the night intervenes; while noonday falls between morning and evening. Consequently, if there be a morning and an evening knowledge in the angels, for the same reason it appears that there ought to be a noonday and a night knowledge.

Obj. 3: Further, knowledge is diversified according to the difference of the objects known: hence the Philosopher says (De Anima iii, text. 38), "The sciences are divided just as things are." But there is a threefold existence of things: to wit, in the Word; in their own natures; and in the angelic knowledge, as Augustine observes (Gen. ad lit. ii, 8). If, therefore, a morning and an evening knowledge be admitted in the angels, because of the existence of things in the Word, and in their own nature, then there ought to be admitted a third class of knowledge, on account of the existence of things in the angelic mind.

I answer that, The expression "morning" and "evening" knowledge was devised by Augustine; who interprets the six days wherein God made all things, not as ordinary days measured by the solar circuit, since the sun was only made on the fourth day, but as one day, namely, the day of angelic knowledge as directed to six classes of things. As in the ordinary day, morning is the beginning, and evening the close of day, so, their knowledge of the primordial being of things is called morning knowledge; and this is according as things exist in the Word. But their knowledge of the very being of the thing created, as it stands in its own nature, is termed evening knowledge; because the being of things flows from the Word, as from a kind of primordial principle; and this flow is terminated in the being which they have in themselves.

Reply Obj. 1: Evening and morning knowledge in the angelic knowledge are not taken as compared to an admixture of darkness, but as compared to beginning and end. Or else it can be said, as Augustine puts it (Gen. ad lit. iv, 23), that there is nothing to prevent us from calling something light in comparison with one thing, and darkness with respect to another. In the same way the life of the faithful and the just is called light in comparison with the wicked, according to Eph. 5:8: "You were heretofore darkness; but now, light in the Lord": yet this very life of the faithful, when set in contrast to the life of glory, is termed darkness, according to 2 Pet. 1:19: "You have the firm prophetic word, whereunto you do well to attend, as to a light that shineth in a dark place." So the angel's knowledge by which he knows things in their own nature, is day in comparison with ignorance or error; yet it is dark in comparison with the vision of the Word.

Reply Obj. 2: The morning and evening knowledge belong to the day, that is, to the enlightened angels, who are quite apart from the darkness, that is, from the evil spirits. The good angels, while knowing the creature, do not adhere to it, for that would be to turn to darkness and to night; but they refer this back to the praise of God, in Whom, as in their principle, they know all things. Consequently after "evening" there is no night, but "morning"; so that morning is the end of the preceding day, and the beginning of the following, in so far as the angels refer to God's praise their knowledge of the preceding work. Noonday is comprised under the name of day, as the middle between the two extremes. Or else the noon can be referred to their knowledge of God Himself, Who has neither beginning nor end.

Objection 1: It would seem that the morning and the evening knowledge are one. For it is said (Gen. 1:5): "There was evening and morning, one day." But by the expression "day" the knowledge of the angels is to be understood, as Augustine says (Gen. ad lit. iv, 23). Therefore the morning and evening knowledge of the angels are one and the same.

Obj. 2: Further, it is impossible for one faculty to have two operations at the same time. But the angels are always using their morning knowledge; because they are always beholding God and things in God, according to Matt. 18:10. Therefore, if the evening knowledge were different from the morning, the angel could never exercise his evening knowledge.

Obj. 3: Further, the Apostle says (1 Cor. 13:10): "When that which is perfect is come, then that which is in part shall be done away." But, if the evening knowledge be different from the morning, it is compared to it as the less perfect to the perfect. Therefore the evening knowledge cannot exist together with the morning knowledge.

I answer that, As was observed (A. 6), the evening knowledge is that by which the angels know things in their proper nature. This cannot be understood as if they drew their knowledge from the proper nature of things, so that the preposition "in" denotes the form of a principle; because, as has been already stated (Q. 55, A. 2), the angels do not draw their knowledge from things. It follows, then, that when we say "in their proper nature" we refer to the aspect of the thing known in so far as it is an object of knowledge; that is to say, that the evening knowledge is in the angels in so far as they know the being of things which those things have in their own nature.

Now they know this through a twofold medium, namely, by innate ideas, or by the forms of things existing in the Word. For by beholding the Word, they know not merely the being of things as existing in the Word, but the being as possessed by the things themselves; as God by contemplating Himself sees that being which things have in their own nature. It, therefore, it be called evening knowledge, in so far as when the angels behold the Word, they know the being which things have in their proper nature, then the morning and the evening knowledge are essentially one and the same, and only differ as to the things known. If it be called evening knowledge, in so far as through innate ideas they know the being which things have in their own natures, then the morning and the evening knowledge differ. Thus Augustine seems to understand it when he assigns one as inferior to the other.

Reply Obj. 1: The six days, as Augustine understands them, are taken as the six classes of things known by the angels; so that the day's unit is taken according to the unit of the thing understood; which, nevertheless, can be apprehended by various ways of knowing it.

Reply Obj. 2: There can be two operations of the same faculty at the one time, one of which is referred to the other; as is evident when the will at the same time wills the end and the means to the end; and the intellect at the same instant perceives principles and conclusions through those principles, when it has already acquired knowledge. As Augustine says (Gen. ad lit. iv, 24), the evening knowledge is referred to the morning knowledge in the angels; hence there is nothing to hinder both from being at the same time in the angels.

Reply Obj. 3: On the coming of what is perfect, the opposite imperfect is done away: just as faith, which is of the things that are not seen, is made void when vision succeeds. But the imperfection of the evening knowledge is not opposed to the perfection of the morning knowledge. For that a thing be known in itself, is not opposite to its being known in its cause. Nor, again, is there any inconsistency in knowing a thing through two mediums, one of which is more perfect and the other less perfect; just as we can have a demonstrative and a probable medium for reaching the same conclusion. In like manner a thing can be known by the angel through the uncreated Word, and through an innate idea. _______________________