«CAELI DEUS SANCTISSIME». — This is the hymn of Wednesday Vespers, attributed to s. Ambrogio, but with not very solid grounds. The dying day inspires the poet with feelings of emotion. After a brief description of the sunset and the last glimmers
of light, the reference to Gen. 1:14–19 is full of meaning: on the fourth day, the creation of the «luminaria magna»—the sun, the moon, and the stars that give life and light to creation—is placed. The entire composition takes the form of a prayer, and the fourth stanza pleads for the flight of night from the heart, of darkness from the intellect, and of the bonds of guilt from the conscience. Silverio Mattei