O heilges Geist- und Wasserbad in G major, BWV 165

Bach had taken up regular cantata composition a year before when he was promoted to concertmaster at the Weimar court, writing one cantata per month to be performed in the Schlosskirche, the court chapel in the ducal Schloss. O heilges Geist- und Wasserbad was his first cantata for Trinity Sunday, the feast day marking the end of the first half of the liturgical year. The libretto by the court poet Salomo Franck is based on the day's prescribed gospel reading about the meeting of Jesus and Nicodemus. It is close in content to the gospel and connects the concept of the Trinity to baptism.