Comment: Our actions are pleasing to God when done for the pure intent of satisfying His Will and for His Glory. Thomas cautions us that our faith can become weak when not accompanied by good works. Those who have true charity (love), have truly learned that all else, again, is vanity.
Book 1, Chapter 15: On Works of Charity
Nothing must be done that is evil even if done for the love of another or for worldly good. Sometimes a good work must be postponed, or be altered in order to help those suffering. In this way, a good work is not destroyed but finished.
No work has its benefits without love, but whatever is done in charity (love), regardless of how small and lowly, brings forth good fruit. For God always considers what you are able to do, more than the greatness of what you have done.
2. Whoever does much, loves much. Those who do much, do well (Jas 2:14, ff). Those who do well minister to the public good rather than to their own self-interest. Oftentimes that which seems to be charity is really carnality, because the charitable work springs from your natural inclinations toward self-will, the hope of repayment, and desire for gain.
3. Whoever has true and perfect charity, does not seek their own good but desires that God alone be glorified. No one is envied here because there is no longing for selfish joy. Likewise, you have no desire to rejoice in yourself, but rather you long to be blessed in God as the highest good. Ascribe to praise God alone. He is the Fountain from which all goodness flows and as the End, the Peace, and the Joy of all Saints. Oh, you who have but a spark of true charity, have truly learned that all worldly things are full of vanity.