The chant Media Vita in Morte Sumus [In the midst of life we are in death], also known as the Antiphon of the Sinners, was originally a part of the Compline service for the Fourth Sunday of Lent. The text of the hymn is attributed to Notker the Sammerer, learned Benedictine of St. Gall, Sitzerland, who died in 912. According to the tradition, Notker wrote the hymn watching workmen risking their lives while building a bridge. Recent scholarship, however, cast doubt on Notker authorship and attributes the chant to the 12th century.
Media Vita was incorporated into some forms of the liturgy for the deceased as early as in the 13th century, and later became part of the Burial Service of the Anglican Church. In our times Media Vita continues to be used as antiphon on the Third and Fifth Sundays of Lent.
Outside the liturgical use, there was a tradition to sing Media vita to ask God for help in times of public need, or as a battle hymn.
–Dr. Andrzej Zahorski
Be sure to check out Dr. Andrzej Zahorski’s full article on In Media Vita here.