Thomas Aquinas

“ If you look at its origin, the substance of the soul is more precious than the body: but if at the sin of transgression, on account of its intelligence it is worse than the body. Now I know and declare that Christ is perfect wisdom, nor have I any doubt that He is most loving; and because of the first of these He did not despise what was better and more capable of prudence; and because of the second He protected what was most wounded." Thirdly, this position is against the truth of the Incarnation. For flesh and the other parts of man receive their species through the soul. ”

“ For since the body is proportioned to the soul as matter to its proper form, it is not truly human flesh if it is not perfected by human, i.e. a rational soul. And hence if Christ had had a soul without a mind, He would not have had true human flesh, but irrational flesh, since our soul differs from an animal soul by the mind alone. ”

“ Theophilus: "Just as the best workmen are esteemed not merely for displaying their skill in precious materials, but very often because by making use of the poorest . . . lay and commonest earth, they show the power of their craft; so the best of all workmen, the Word of God, did not come down to us by taking a heavenly body of some most precious matter, but shewed the greatness of His skill in clay."
Art. 3 - Whether the Son of God assumed a soul? ”

“ For since the form of man is a natural thing, it requires determinate matter, to wit, flesh and bones, which must be placed in the definition of man, as is plain from the Philosopher (Metaph. vii, 39) . Secondly, because this would lessen the truth of such things as Christ did in the body. For since a heavenly body is impassible and incorruptible, as is proved De Coel. i, 20, if the Son of God had assumed a heavenly body, He would not have truly hungered or thirsted, nor would he have undergone His passion and death. ”

“ Secondly, it is inconsistent with the purpose of the Incarnation, which is the justification of man from sin. For the human soul is not capable of sin nor of justifying grace except through the mind. Hence it was especially necessary for the mind to be assumed. Hence Damascene says (De Fide Orth. iii, 6) that "the Word of God assumed a body and an intellectual and rational soul," and adds afterwards: "The whole was united to the whole, that He might bestow salvation on me wholly; for what was not assumed is not curable." ”

“ For if His body was not real but imaginary, He neither underwent a real death, nor of those things which the Evangelists recount of Him, did He do any in very truth, but only in appearance; and hence it would also follow that the real salvation of man has not taken place; since the effect must be proportionate to the cause. The third reason is taken from the dignity of the Person assuming, Whom it did not become to have anything fictitious in His work, since He is the Truth. ”