Dienstag aus Licht (Tuesday from Light) is an opera by Karlheinz Stockhausen in a greeting and two acts, with a farewell, and was the fourth of seven to be completed for the opera cycle Licht: Die sieben Tage der Woche (Light: The Seven Days of the Week). It was begun in 1977 and completed from 1988 to 1991, to a libretto by the composer. The main theme of Dienstag is the struggle between the protagonist Michael and his antagonist Lucifer (with the feminine character Eve appearing in a more tangential role, trying to broker a peace between them or mourning the carnage). The first Act portrays this competition in the form of a "time game", in which the two combatants employ humorous tactics and feints in orders to stop/start time's march. This initial "fight by proxy" leads to the more direct 2nd (and final) Act, which portrays all-out war using mobile sound-warriors in an apocalyptic 3D sound environment.