The perfection of the angels in the order of grace and of glory
Objection 1. It would seem that natural knowledge and love do not remain in the beatified angels. For it is said (1 Corinthians 13:10): "When that which is perfect is come, then that which is in part shall be done away." But natural love and knowledge are imperfect in comparison with beatified knowledge and love. Therefore, in beatitude, natural knowledge and love cease.
Objection 2. Further, where one suffices, another is superfluous. But the knowledge and love of glory suffice for the beatified angels. Therefore it would be superfluous for their natural knowledge and love to remain.
Objection 3. Further, the same faculty has not two simultaneous acts, as the same line cannot, at the same end, be terminated in two points. But the beatified angels are always exercising their beatified knowledge and love; for, as is said Ethic. i, 8, happiness consists not in habit, but in act. Therefore there can never be natural knowledge and love in the angels.
On the contrary, So long as a nature endures, its operation remains. But beatitude does not destroy nature, since it is its perfection. Therefore it does not take away natural knowledge and love.
I answer that, Natural knowledge and love remain in the angels. For as principles of operations are mutually related, so are the operations themselves. Now it is manifest that nature is to beatitude as first to second; because beatitude is superadded to nature. But the first must ever be preserved in the second. Consequently nature must be preserved in beatitude: and in like manner the act of nature must be preserved in the act of beatitude.
Reply to Objection 1. The advent of a perfection removes the opposite imperfection. Now the imperfection of nature is not opposed to the perfection of beatitude, but underlies it; as the imperfection of the power underlies the perfection of the form, and the power is not taken away by the form, but the privation which is opposed to the form. In the same way, the imperfection of natural knowledge is not opposed to the perfection of the knowledge in glory; for nothing hinders us from knowing a thing through various mediums, as a thing may be known at the one time through a probable medium and through a demonstrative one. In like manner, an angel can know God by His essence, and this appertains to his knowledge of glory; and at the same time he can know God by his own essence, which belongs to his natural knowledge.
Reply to Objection 2. All things which make up beatitude are sufficient of themselves. But in order for them to exist, they presuppose the natural gifts; because no beatitude is self-subsisting, except the uncreated beatitude.
Reply to Objection 3. There cannot be two operations of the one faculty at the one time, except the one be ordained to the other. But natural knowledge and love are ordained to the knowledge and love of glory. Accordingly there is nothing to hinder natural knowledge and love from existing in the angel conjointly with those of glory.
Source: Summa Theologica (New Advent)