ess to health, as
stated above (Q. 71, A. 1, ad 3). Now, man, by force of his nature,
can rise from illness to health, without the external help of
medicine, since there still remains in him the principle of life,
from which the natural operation proceeds. Hence it seems that, with
equal reason, man may be restored by himself, and return from the
state of sin to the state of justice without the help of external
grace.

Obj. 3: Further, every natural thing can return by itself to the act
befitting its nature, as hot water returns by itself to its natural
coldness, and a stone cast upwards returns by itself to its natural
movement. Now a sin is an act against nature, as is clear from
Damascene (De Fide Orth. ii, 30). Hence it seems that man by himself
can return from sin to the state of justice.

_On the contrary,_ The Apostle says (Gal. 2:21; Cf. Gal. 3:21): "For
if there had been a law given which could give life--then Christ died
in vain," i.e. to no purpose. Hence with equal reason, if man has a
nature, whereby he can he justified, "Christ died in vain," i.e. to
no purpose. But this cannot fittingly be said. Therefore by himself
he cannot be justified, i.e. he cannot return from a state of sin to
a state of justice.

_I answer that,_ Man by himself can no wise rise from sin without the
help of grace. For since sin is transient as to the act and abiding
in its guilt, as stated above (Q. 87, A. 6), to rise from sin is not
the same as to cease the act of sin; but to rise from sin means that
man has restored to him what he lost by sinning. Now man incurs a
triple loss by sinning, as was clearly shown above (Q. 85, A. 1; Q.
86, A. 1; Q. 87, A. 1), viz. stain, corruption of natural good, and
debt of punishment. He incurs a stain, inasmuch as he forfeits the
lustre of grace through the deformity of sin. Natural good is
corrupted, inasmuch as man's nature is disordered by man's will not
being subject to God's; and this order being overthrown, the
consequence is that the whole nature of sinful man remains
disordered. Lastly, there is the debt of punishment, inasmuch as by
sinning man deserves everlasting damnation.

Now it is manifest that none of these three can be restored except by
God. For since the lustre of grace springs from the shedding of
Divine light, this lustre cannot be brought back, except God sheds
His light anew: hence a habitual gift is necessary, and this is the
light of grace. Likewise, the order of na