is the same reason that prescribes what is good and forbids what is evil.  On the other hand if a man’s reason or conscience tells him that he is bound by precept to do what is evil in itself; or that what is good in itself, is forbidden, then his reason or conscience errs.  In like manner if a man’s reason or conscience tell him, that what is indifferent in itself, for instance to raise a straw from the ground, is forbidden or commanded, his reason or conscience errs.  They say, therefore, that reason or conscience when erring in matters of indifference, either by commanding or by forbidding them, binds:  so that the will which is at variance with that erring reason is evil and sinful.  But they say that when reason or conscience errs in commanding what is evil in itself, or in forbidding what is good in itself and necessary for salvation, it does not bind; wherefore in such cases the will which is at variance with erring reason or conscience is not evil.

But this is unreasonable.  For in matters of indifference, the will that is at variance with erring reason or conscience, is evil in some way on account of the object, on which the goodness or malice of the will depends; not indeed on account of the object according as it is in its own nature; but according as it is accidentally apprehended by reason as something evil to do or to avoid.  And since the object of the will is that which is proposed by the reason, as stated above (A. 3), from the very fact that a thing is proposed by the reason as being evil, the will by tending thereto becomes evil.  And this is the case not only in indifferent matters, but also in those that are good or evil in themselves.  For not only indifferent matters can receive the character of goodness or malice accidentally; but also that which is good, can receive the character of evil, or that which is evil, can receive the character of goodness, on account of the reason apprehending it as such.  For instance, to refrain from fornication is good:  yet the will does not tend to this good except in so far as it is proposed by the reason.  If, therefore, the erring reason propose it as an evil, the will tends to it as to something evil.  Consequently the will is evil, because it wills evil, not indeed that which is evil in itself, but that which is evil accidentally, through being apprehended as such by the reason.  In like manner, to believe in Christ is good in itself, and necessary for salvation:  but the will does not tend thereto, except inasmuch as it is proposed by the reason.  Consequently if it be proposed by the reason as something evil, the will tends to it as to something evil:  not as if it were evil in itself, but because it is evil accidentally, through the apprehension of the reason.  Hence the Philosopher says (Ethic. vii, 9) that “properly speaking the incontinent man is one who does not follow right reason; but accidentally, he is also one who does not follow false reason.”  We must therefore conclude that, absolutely speaking, every will at variance with reason, whether right or erring, is always evil.