Thomas Aquinas

“ Hence for there to be contrariety of wills in anyone it is necessary, first, that the diversity of wills should regard the same. For if the will of one regards the doing of something with reference to some universal reason, and the will of another regards the not doing the same with reference to some particular reason, there is not complete contrariety of will, e.g. when a judge wishes a brigand to be hanged for the good of the commonwealth, and one of the latter's kindred wishes him not to be hanged on account of a private love, there is no contrariety of wills ”

“ For an inanimate instrument, as an axe or a saw, is moved by the craftsman with only a corporeal movement; but an instrument animated by a sensitive soul is moved by the sensitive appetite, as a horse by its rider; and an instrument animated with a rational soul is moved by its will, as by the command of his lord the servant is moved to act, the servant being like an animate instrument, as the Philosopher says (Polit. i, 2,4; Ethic. viii, 11) . And hence it was in this manner that the human nature of Christ was the instrument of the Godhead, and was moved by its own will. ”

“ Hence we must say that if we are speaking of the power of the will, in Christ there is but one human will, essentially so called and not by participation; but if we are speaking of the will as an act, we thus distinguish in Christ a will as nature, which is called {thelesis}, and a will as reason, which is called {boulesis}. ”

“ Consequently it must be allowed that in Christ there was a sensual appetite, or sensuality. But it must be borne in mind that sensuality or the sensual appetite, inasmuch as it naturally obeys reason, is said to be "rational by participation," as is clear from the Philosopher (Ethic. i, 13) . And because "the will is in the reason," as stated above, it may equally be said that the sensuality is "a will by participation." ”

“ Choice presupposes counsel; yet it follows counsel only as determined by judgment. For what we judge to be done, we choose, after the inquiry of counsel, as is stated (Ethic. iii, 2,3) . Hence if anything is judged necessary to be done, without any preceding doubt or inquiry, this suffices for choice. ”

“ But in the same way as regards man's apprehension, we hold the difference of reason and intellect; both of which were in Christ. Therefore there was a double will in Him, one intellectual and the other rational. ”

“ For if the diversity exists as regards diverse things, and in diverse subjects, this would not suffice for the nature of contrariety, nor even for the nature of contradiction, e.g. if a man were well formed or healthy as regards his hand, but not as regards his foot. ”