COLOGNE, Germany

AFTER a triumphant premiere at the New York Philharmonic in 1971, the story goes, the German composer Karlheinz Stockhausen was approached by a strange figure. Clad in a goatskin cape, carrying a staff and holding a thick book, the man stood out even amid the colorful throng of hippies and bohemians who had shown up to hear Stockhausen conduct his “Hymnen.” The stranger introduced himself, played a self-made flute and offered up the heavy tome under his arm, asking Stockhausen to become “the minister of sound transmission.”

So he did. The quasi-Christian mix of science and religion in “The Urantia Book” — the text Stockhausen bought from the wizardly figure — became the spiritual basis for a huge operatic cycle, “Licht” (“Light”). Written from 1977 to 2003, “Licht” exceeds even Wagner’s “Ring” cycle in its epic proportions, comprising seven full operas, one for each day of the week, and clocking in at 29 hours total.

Stockhausen died in 2007, without having seen “Licht” staged in its entirety. But his work has found new life at the Cologne Opera, which in recent weeks presented the culmination of the cycle, “Sonntag” (“Sunday”). To house the production the company built two theaters within the cavernous Staatenhaus am Rheinpark, part of the city’s exhibition center.

The local ensemble musikFabrik joined forces with the Catalan directorial team La Fura dels Baus and several longtime Stockhausen collaborators, including the flutist and electronics specialist Kathinka Pasveer and the conductor Peter Rundel. Although various scenes from “Sonntag” have been performed in concert, the Cologne performances constituted the premiere of the complete opera.