59 But, before we investigate the meaning and occasion of these words, let us first appeal to the judgment of common sense. Is it credible, that He, Who stands to all things as the Author of their present and future, should not know all things? If all things are through and in Christ, and in such a way through Christ that they are also in Him, must not that, which is both in Him and through Him, be also in His knowledge, when that knowledge, by virtue of a nature which cannot be nescient, habitually apprehends what is neither in, nor through Him?
But that which derives from Him alone its origin, and has in Him alone the efficient cause of its present state and future development, can that be beyond the ken of His nature, through which is effected, and in which is contained, all that it is and shall be? Jesus Christ knows the thoughts of the mind, as it is now, stirred by present motives, and as it will be tomorrow, aroused by the impulse of future desires. Hear the witness of the Evangelist, For Jesus knew from the beginning who they were that believed not, and who it was that should betray Him. By its virtue His nature could perceive the unborn future, and foresee the awakening of passions yet dormant in the mind: do you believe that it did not know what is through itself, and within itself?
He is Lord of all that belongs to others, is He not Lord of His own? Remember what is written of Him, All things have been created through Him, and in Him: and He is before all things: or again, For it was the good pleasure of the Father, that in Him should all the fullness dwell, and through Him to reconcile all things unto Himself, all fullness is in Him, all things were made through Him, and are reconciled in Him, and for that day of reconciliation we wait expectant; did He not, then, know it, when its time was in His hands, and fixed by His mystery, for it is the day of His coming, of which the Apostle wrote, When Christ, Who is your life, shall be manifested, then shall you also with Him be manifested in glory. No one is ignorant of that which is through himself and within himself: shall Christ come, and does He not know the day of His coming?
It is His day, for the same Apostle says, The day of the Lord shall come as a thief in the night: can we believe, then, that He did not know it? Human natures, so far as in them lies, foresee what they determine to do: knowledge of the end desired accompanies the desire to act: does not He Who is born God, know what is in, and through, Himself? The times are through Him, the day is in His hand, for the future is constituted through Him, and the Dispensation of His coming is in His power: is His understanding so dull, that the sense of His torpid nature does not tell Him what He has Himself determined?
Is He like the brute and the beast, which, animated by no reason or foresight, not even conscious of acting but driven to and fro by the impulse of irrational desire, proceed to their end with fortuitous and uncertain course?
Source: On the Trinity (New Advent)