The readings for Saints’ feast days are obviously chosen for their relevance, but I think few are as fitting to the day as this Epistle for the Feast of St. Thomas Aquinas (Wisdom 7: 7-14):

Wherefore I wished, and understanding was given me: and I called upon God, and the spirit of wisdom came upon me: And I preferred her before kingdoms and thrones, and esteemed riches nothing in comparison of her. Neither did I compare unto her any precious stone: for all gold, in comparison of her, is as a little sand; and silver, in respect to her, shall be counted as clay. I loved her above health and beauty, and chose to have her instead of light: for her light cannot be put out. Now all good things came to me together with her, and innumerable riches through her hands, and I rejoiced in all these: for this wisdom went before me, and I knew not that she was the mother of them all. Which I have learned without guile, and communicate without envy, and her riches I hide not. For she is an infinite treasure to men: which they that use, become the friends of God, being commended for the gifts of discipline.