"Christus, du Licht vom wahren Licht" (Christ, you light from true light) is a Catholic hymn in German, a paraphrase of the medieval Latin hymn "Summi parentis unica".
It is a song about the apostles.
[1] In the common Catholic hymnal in German, Gotteslob, it is GL 546.
[2] The text was adapted in Münsterschwarzach Abbey, to a 1548 melody by Johann Leisentritt, revised by Erhard Quack in 1941.
[1]