c. vii, 4, 7) does not moderate any passions, but consists
merely in a certain firmness of reason and will. But perseverance,
considered as a virtue, moderates certain passions, namely fear of
weariness or failure on account of the delay. Hence this virtue, like
fortitude, is in the irascible.

Reply Obj. 3: Augustine speaks there of perseverance, as denoting,
not a virtuous habit, but a virtuous act sustained to the end,
according to Matt. 24:13, "He that shall persevere to the end, he
shall be saved." Hence it is incompatible with such like perseverance
for it to be lost, since it would no longer endure to the end.
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THIRD ARTICLE [II-II, Q. 137. Art. 3]

Whether Constancy Pertains to Perseverance?

Objection 1: It seems that constancy does not pertain to
perseverance. For constancy pertains to patience, as stated above (Q.
137, A. 5): and patience differs from perseverance. Therefore
constancy does not pertain to perseverance.

Obj. 2: Further, "virtue is about the difficult and the good." Now it
does not seem difficult to be constant in little works, but only in
great deeds, which pertain to magnificence. Therefore constancy
pertains to magnificence rather than to perseverance.

Obj. 3: Further, if constancy pertained to perseverance, it would
seem nowise to differ from it, since both denote a kind of
unchangeableness. Yet they differ: for Macrobius (In Somn. Scip. i)
condivides constancy with firmness by which he indicates
perseverance, as stated above (Q. 128, A. 6). Therefore constancy
does not pertain to perseverance.

_On the contrary,_ One is said to be constant because one stands to a
thing. Now it belongs to perseverance to stand to certain things, as
appears from the definition given by Andronicus. Therefore constancy
belongs to perseverance.

_I answer that,_ Perseverance and constancy agree as to end, since it
belongs to both to persist firmly in some good: but they differ as to
those things which make it difficult to persist in good. Because the
virtue of perseverance properly makes man persist firmly in good,
against the difficulty that arises from the very continuance of the
act: whereas constancy makes him persist firmly in good against
difficulties arising from any other external hindrances. Hence
perseverance takes precedence of constancy as a part of fortitude,
because the difficulty arising from continuance of action is more
intrinsic to the act of virtue than tha