Gratitude: https://www.newadvent.org/summa/3106.htm
Ingratitude: https://www.newadvent.org/summa/3107.htm
Incidentally many secular people have noted "benefits" of gratitude to health and well-being, besides the spiritual aspect of gratitude as noted in above writings.
Aquinas leading to Ron Paul? His views of natural law? Aquinas may have been a bit against Ron Paul's classical liberalism, although there is some overlap; Aquinas may have been a little more authoritarian.
However, interestingly enough (at least to me), Aquinas did advocate for or consider some things that a lot of moderns shy away from. For example, he advocated for legalizing prostitution, which Ron Paul would also probably be for, because he argued criminalizing it would create a worse black market (I think? I know he did think prostitution should be legal). He also considered the possibility of "tyrannicide" or killing a truly tyrannical king:
> In Thomas Aquinas's commentary on the Sentences of Peter Lombard, Aquinas gave a defense not only of disobedience to an unjust authority, using as an example Christian martyrs in the Roman Empire, but also of "one who liberates his country by killing a tyrant."
https://infogalactic.com/info/Tyrannicide
I haven't read the source material, but it seems interesting to me how "protestant puritanism" and "leftwing authortarianism" can end up being so anti-liberty at times, when they sometimes otherwise speak as though they are for people's freedoms.