“…we may conclude that the Angelus in its origin was an imitation of the monks' night prayers and that it had probably nothing directly to do with the curfew bell.”
The Angelus
From the early Church Fathers to now.
V. The Angel of the Lord declared unto Mary. R. And she conceived of the Holy Spirit.
V. Behold the handmaid of the Lord. R. Be it done unto me according to thy word.
V. And the Word was made flesh. R. And dwelt among us.
V. Pray for us, O holy Mother of God. R. That we may be made worthy of the promises of Christ. (A Hail Mary is said after each of the first three versicles.)
The custom of a triple Hail Mary at the sound of the evening bell arises in the Franciscan and monastic houses, in memory of the angelic salutation and the Incarnation.
The evening Angelus is recommended and indulgenced by Pope John XXII in 1318, and again in 1327 — the first documented papal act for the devotion.
Associated with prayer for peace, the Angelus bell is formally commended by Louis XI of France in 1475 for that special object.
By the sixteenth century the Angelus is rung and prayed three times each day — morning, noon, and evening — throughout the Latin Church.
The in-app commentary runs from the Fathers to the early-modern record, then stops — that's where the public-domain sources end, not where the reading does. For the modern reading, follow the sources directly.