Summa summae S. Thomae, Tomus II

I say 1°: The will is the subject of sin formally taken ¹; because the immanent act is in that power from which it is elicited. But sin is an immanent act; for it is to desire or to know, and insofar as it is voluntary it is elicited by the will. Therefore

I say 2°: Not the will alone, but also the sensitive appetite ² and reason are the subject of sin formally taken; not however the members or external senses.

It is proved of the first part. If the sensitive appetite could not be the subject of formal sin, the reason would be that it is not intrinsically free, but only denominatively free from without.

But the assumption is false. Therefore. — The major is the adversaries'. — Proof of the minor: The sensitive appetite in man, from its immediate conjunction with the will and subordination to it, participates a certain liberty, although imperfect. Therefore. — Proof of the antecedent 1° from our Author, here a. 3, ad 1 ³, and in II Sentent., dist. 21, q. 1, a. 2, ad 5, where he says: « The concupiscible has a certain liberty..., according as it can obey the command of reason. »

2° The cogitative, from conjunction with intellect, participates the power of discoursing about singulars, as the Author teaches I p., q. 18, a. 4, o. Therefore likewise the sensitive appetite, from conjunction with the will, participates a certain liberty.

3° Such is the mode of divine providence, to connect the orders of things so among themselves that, according to the saying drawn from St. Dionysius, the supreme of the inferior order may touch the lowest of the superior: thus the noblest bodies, namely the heavenly, participate the incorruptibility of spirits; thus the most excellent of elements, fire, imitates the motion of living beings; and so of the rest. Why then should not the sensitive appetite in man, from its immediate conjunction with the will, participate something of its liberty and amplitude?

The same must be said of reason. Insofar as it precedes the will, it is radically free, since from its indifferent judgment liberty originates; insofar however as it follows the will, it participates and expresses its liberty. Whence our Author, here a. 5, ad 2: « The will, he says, in a certain way moves and precedes reason, and reason in a certain way the will: whence the motion of the will can be called rational, and the act of reason can be called voluntary. And according to this sin is found in reason, either as it is a defect thereof voluntary, or as the act of reason is principle of the act of will. »

It is proved of the second part ⁴ : The members or external senses are not intrinsically free, but only denominatively so from without, from the will, by which they are moved despotically, like the servant who is acted upon and does not act; whence, in respect of sin formally taken, they are not active principles, but only organs and instruments. Therefore.