2: Further, proportionate repayment belongs to commutative
justice, according to the Philosopher (Ethic. v, 4). Now the purpose
of giving thanks is repayment (Ethic. 5, 4). Therefore thanksgiving,
which belongs to gratitude, is an act of justice. Therefore gratitude
is not a special virtue, distinct from other virtues.

Obj. 3: Further, acknowledgment of favor received is requisite for
the preservation of friendship, according to the Philosopher (Ethic.
viii, 13; ix, 1). Now friendship is associated with all the virtues,
since they are the reason for which man is loved. Therefore
thankfulness or gratitude, to which it belongs to repay favors
received, is not a special virtue.

_On the contrary,_ Tully reckons thankfulness a special part of
justice (De Invent. Rhet. ii).

_I answer that,_ As stated above (I-II, Q. 60, A. 3), the nature of
the debt to be paid must needs vary according to various causes
giving rise to the debt, yet so that the greater always includes the
lesser. Now the cause of debt is found primarily and chiefly in God,
in that He is the first principle of all our goods: secondarily it is
found in our father, because he is the proximate principle of our
begetting and upbringing: thirdly it is found in the person that
excels in dignity, from whom general favors proceed; fourthly it is
found in a benefactor, from whom we have received particular and
private favors, on account of which we are under particular
obligation to him.

Accordingly, since what we owe God, or our father, or a person
excelling in dignity, is not the same as what we owe a benefactor
from whom we have received some particular favor, it follows that
after religion, whereby we pay God due worship, and piety, whereby we
worship our parents, and observance, whereby we worship persons
excelling in dignity, there is thankfulness or gratitude, whereby we
give thanks to our benefactors. And it is distinct from the foregoing
virtues, just as each of these is distinct from the one that
precedes, as falling short thereof.

Reply Obj. 1: Just as religion is superexcelling piety, so is it
excelling thankfulness or gratitude: wherefore giving thanks to God
was reckoned above (Q. 83, A. 17) among things pertaining to religion.

Reply Obj. 2: Proportionate repayment belongs to commutative justice,
when it answers to the legal due; for instance when it is contracted
that so much be paid for so much. But the repayment that belongs to
the virtue