Reply Obj. 3:  The last end moves the will necessarily, because it is the perfect good.  In like manner whatever is ordained to that end, and without which the end cannot be attained, such as “to be” and “to live,” and the like.  But other things without which the end can be gained, are not necessarily willed by one who wills the end:  just as he who assents to the principle, does not necessarily assent to the conclusions, without which the principles can still be true. ________________________

THIRD ARTICLE [I-II, Q. 10, Art. 3]

Whether the Will Is Moved, of Necessity, by the Lower Appetite?

Objection 1:  It would seem that the will is moved of necessity by a passion of the lower appetite.  For the Apostle says (Rom. 7:19):  “The good which I will I do not; but the evil which I will not, that I do”:  and this is said by reason of concupiscence, which is a passion.  Therefore the will is moved of necessity by a passion.

Obj. 2:  Further, as stated in Ethic. iii, 5, “according as a man is, such does the end seem to him.”  But it is not in man’s power to cast aside a passion at once.  Therefore it is not in man’s power not to will that to which the passion inclines him.

Obj. 3:  Further, a universal cause is not applied to a particular effect, except by means of a particular cause:  wherefore the universal reason does not move save by means of a particular estimation, as stated in De Anima iii, 11.  But as the universal reason is to the particular estimation, so is the will to the sensitive appetite.  Therefore the will is not moved to will something particular, except through the sensitive appetite.  Therefore, if the sensitive appetite happen to be disposed to something, by reason of a passion, the will cannot be moved in a contrary sense.

On the contrary, It is written (Gen. 4:7):  “Thy lust [Vulg.  ’The lust thereof’] shall be under thee, and thou shalt have dominion over it.”  Therefore man’s will is not moved of necessity by the lower appetite.

I answer that, As stated above (Q. 9, A. 2), the passion of the sensitive appetite moves the will, in so far as the will is moved by its object:  inasmuch as, to wit, man through being disposed in such and such a way by a passion, judges something to be fitting and good, which he would not judge thus were it not for the passion.  Now this influence of a passion on man occurs in two ways.  First, so that his reason is wholly bound, so that he has not the use of reason:  as happens in those who through a violent access of anger or concupiscence become furious or insane, just as they may from some other bodily disorder; since such like passions do not take place without some change in the body.  And of such the same is to be said as of irrational animals, which follow, of necessity, the impulse of their passions:  for in them there is neither movement of reason, nor, consequently, of will.