"Angels execute the divine plan"

“GOD’s universal providence works through secondary causes…. The world of pure spirits stretches between the Divine Nature and the world of human beings; because Divine Wisdom has ordained that the higher should look after the lower, angels execute the divine plan for human salvation: they are our guardians, who free us when hindered and help to bring us home.”

~St. Thomas Aquinas: Commentary on the Sentences, 2, 11, 1, 1.

Rucellai Madonna (detail: Angel), by Duccio di Buoninsegna.

Tempera on wood, 1285; Galleria degli Uffizi, Florence.