I would say that his controlling idea is based on the Aparecida document where it is written, "The Eucharist is the vital center of the universe, able to satisfy our hunger for life and happiness. Whoever eats my flesh and drinks my blood in this happy banquet participates in eternal life, and thus our daily existence is transformed into an extension of the Mass." He then develops the theme of the Eucharist as gift and mission in light of the Church's enduring self-understanding as covenant. He appeals to tradition, some saints and the Mother of God to demonstrate that evangelization is about Eucharistic Presence, sacrifice, and communion. He argues in the key of communio theology.
Much of what we've heard in the last two weeks in his papal addresses and homilies given here.