16 To begin with the topic which we have proposed first to discuss, We cannot refrain, following the counsel of St. Ambrose who says that "no duty is more important than that of returning thanks," from offering our fullest gratitude to Almighty God for the immense benefits that have come through Leo's Encyclical to the Church and to human society. If indeed We should wish to review these benefits even cursorily, almost the whole history of the social question during the last forty years would have to be recalled to mind. These benefits can be reduced conveniently, however, to three main points, corresponding to the three kinds of help which Our Predecessor ardently desired for the accomplishment of his great work of restoration.
Source: Quadragesimo Anno (Vatican.va)