Following the example of the Lord, who frequently sang hymns with his disciples, and encouraged to sing by St Paul, the early Christians praised God in music and song. The first Latin hymns were composed by Hilary of Poitiers. Their metrical complexity and content discouraged their liturgical use by the Church. Thus, St. Ambrose of Milan is considered the first „official” Latin hymnodist. He composed several hymns, still used in the Liturgy of the Hours, which were musicated by himself. These hymns come from the particular circumstances of the Arian controversy and derive, in the main, from the necessity of encouraging „orthodox” Christians in their defence of the Basilica Porziana in Milan. They were designed to guide their prayer at different times of the day. The Author’s text-critical analysis of two of these hymns – Aeterne rerum conditor, sung at dawn (in gallicinium) and Deus, creator omnium, sung at dusk as the lamps were lit (ad horam incensi) – well testifies to the literary and pastoral genius of the Bishop of Milan as he transforms the complex theological reflection of his time into poetry and music, while not only retaining the integrity of the depth of that reflection but also enhancing its aesthetic profile by drawing on a repertoire of images based on the parallelism of cosmic reality and human reality. St Ambrose’s corpus of hymns, together with his prose works, was admired both by his contemporaries and by successive generations. They promoted the flowering of a merciful Christocentricity which, according to the experts, is the most original and attractive feature of his poetry. As is clearly seen in the hymns received into the Divine Office, Ambrose’s singular ability effectively to stimulate the soul to prayer through a powerful and insuperable lyrical inspiration, is capable literally of transforming the daily hours into songs of praise, and explains Petrarch’s habit of rising during the night to sing hymns to the Lord.