"The good of the grace of one soul is greater than the good of the nature of the whole universe"
- St Thomas Aquinas Ia IIa, q.24, a. 3, ad 2
|REALITY—A Synthesis Of Thomistic Thought
by Reginald Garrigou-Lagrange, O. P.
CH35: FREEDOM AND IMPECCABILITY 
Christ's acts of merit and satisfaction presuppose freedom in the proper sense,  not merely spontaneity,  which is found already in the animal. Now it would seem that Christ, if He is to obey freely, must also be able to disobey. Hence the question: how is freedom to be harmonized with absolute impeccability? Impeccability, in Christ, does not mean merely that, in fact, He never sinned. It means that He simply could not sin. He could not for three reasons:
a) by reason of His divine personality, which necessarily excludes sin:
b) by reason of His beatific vision of God's goodness, from which no blessed soul can ever turn aside:
c) by reason of His plentitude of grace, received inamissibly as consequence of the grace of union.
How can Jesus be perfectly free if He is bound by obedience to His Father's will? Dominic Banez  was obliged to study this question profoundly, in answer to certain theologians of his epoch, who tried to safeguard the freedom of Jesus by saying that He had not received from His Father a command to die on the cross for our salvation. This position has defenders even in our own times. Thomists reply that the position contradicts the explicit words of Scripture: "I give My life. This is the command I have received from My Father. That the world may know that I act according to the commandment My Father has given me. Arise, let us go. If you keep My commandments, you will abide in My love, even as I have kept the commandments of My Father, and abide in His love."  Christ became obedient unto death, even to death on the cross. .
Now obedience, properly speaking, has as formal object a command to be fulfilled. And if one says, unjustifiably, that the commands given to Christ were only counsels, how could Christ, being absolutely impeccable, neglect even the counsels of His Father? Hence the question inevitably returns: How can impeccability be harmonized with that real freedom which is presupposed by merit?
The Thomistic reply begins by distinguishing psychological liberty from moral liberty. A command takes away moral liberty, in the sense that disobedience is illicit. But the command, far from taking away psychological liberty, rather builds on this liberty as foundation. The command is given precisely to ensure free acts. No one commands fire to burn, or the heart to beat, or any other necessary act. A command is self-destructive where there is no liberty.
And precept remains precept, and is freely fulfilled, even when he who obeys is impeccable, because the thing commanded (death for our salvation) is good from one viewpoint, and not good, even painful, from another viewpoint. This object is entirely different from the divine goodness clearly seen in the beatific vision. The blessed in heaven are not free to love God whom they see face to face, though they too remain free in other acts, to pray, for example, at this time, or for this person.
Further, if the command to die destroys Christ's liberty, we would have to say the same of all precepts, even of those commanded by the natural law, and thus Christ would have no freedom to obey any precept, and hence could have no merit.
But the difficulty seems to remain. If Christ was free to obey, then He could disobey and thus sin. But faith teaches, not only that He did not sin, but that He could not sin.
In answer let us weigh the following reflections.
1. Liberty of exercise suffices to safeguard the essence of liberty. Man is master of his act when he can either place the act or not place it. Such an act is free, even where there is no choice between contrary acts, hating, say, and loving, or between two disparate ways of attaining an end.
2. The power to sin is not included in the idea of freedom, but is rather the defectibility of our freedom, just as the possibility of error is the defectibility of our intellect. This power to sin does not exist in God who is sovereignly free, nor in the blessed who are confirmed in good. Hence it did not exist in Christ, whose freedom, even here on earth, was the most perfect image of divine freedom. Genuine freedom then does not include disobedience, but rather excludes it. Genuine freedom wills, not evil, but always good. It chooses between two or many objects, none of which is bad, but all good. .
3. Disobedience is not to be confused with the mere absence of obedience. In a sleeping child, for example, though he be the most obedient of children, there is, here and now, the absence of obedience, but no disobedience. Disobedience is a privation, a wrong, a fault, whereas mere absence of obedience is a simple negation. This distinction may seem subtle, but it expresses the truth. Christ, like the blessed in heaven, could not disobey, even by omission or neglect. But His human will, incapable of disobedience, can still see the absence of obedience as good,  as something here and now not necessarily connected with His beatitude. Death on the cross was good for our salvation, but it was a good mixed with non-good, with extreme suffering, physical and moral. Hence it was an object which did not impose necessity on His will. Nor did the divine will impose necessity, since, as we have seen, the precept, by making the omission illicit, removes indeed moral liberty, but, on the contrary, presupposes and preserves physical and psychological liberty.
When then does Jesus love necessarily? He thus loves His Father seen face to face, and hence all else that is, here and now, connected, intrinsically and necessarily, with that supreme beatitude, just as we necessarily will existence, life, and knowledge without which we see that we cannot have happiness. But Jesus willed freely all that was connected, not intrinsically, but only extrinsically, by a command, with beatitude. Death, at once salutary for us and terrible in itself, did not attract necessarily. The command did not change either the nature of the death, or the freedom of the act commanded. Hence Christ's response.
Thus Jesus obeyed freely even though He could not disobey. As distant illustration of this mystery, we may refer to a painful act of obedience in a good religious. He obeys freely, hardly reflecting that he could disobey. Even if he were confirmed in grace, this confirmation would not destroy the freedom of his obedient act. The will of Christ, says St. Thomas,  though it is confirmed in good, is not necessitated by this or that particular good. Hence Christ, like the blessed, chooses by a free will which is confirmed in good. This sentence, in its simplicity, is more perfect than the long commentaries thereon, but the commentaries serve to show the truth hidden in that simplicity. The sinless liberty of Christ is the perfect image of God's sinless liberty. .