Ach Gott, vom Himmel sieh darein (Oh God, look down from heaven),[1] BWV 2, is a chorale cantata composed by Johann Sebastian Bach for the second Sunday after Trinity in 1724.

The church cantata is based on Martin Luther's 1524 hymn "Ach Gott, vom Himmel sieh darein", a paraphrase of Psalm 12.

In the format of Bach's chorale cantata cycle, the words of the hymn are retained unchanged only in the outer movements, while an unknown contemporary librettist paraphrased the inner stanzas for recitatives and arias.

It was part of his duties to supply music for the Sundays and feast days of the liturgical year at four churches of the town, and he decided to compose new cantatas for these occasions.

He wrote Ach Gott, vom Himmel sieh darein as the second cantata of this cycle, which he began a week before with O Ewigkeit, du Donnerwort, BWV 20.

The cantata is based on the chorale in sixth stanzas "Ach Gott, vom Himmel sieh darein", a paraphrase of Psalm 12 by Martin Luther, published in 1524 in the Achtliederbuch, the first Lutheran hymnal.

Bach scored the work for three vocal soloists (alto (A), tenor (T) and bass (B)), a four-part choir, and a Baroque instrumental ensemble: four trombones (Tb), two oboes (Ob), two violins (Vl), viola (Va), and basso continuo (Bc).

[8] The second movement is a secco recitative, "Sie lehren eitel falsche List, was wider Gott und seine Wahrheit ist" (They teach vain, false deceit, which is opposed to God and His truth),[1] which changes to arioso for two lines that resemble the words of the chorale.

The instruments are first silent in the middle section, but return for its transition to the da capo with the words "Im Kreuz und Tod geduldig sein" (be patient in cross-bearing and distress).

[8] The closing chorale, "Das wollst du, Gott, bewahren rein für diesem arg'n Geschlechte" (This, God, you would keep pure before this wicked race; ),[1] is a four-part setting, with all instruments reinforcing the voices.

Other projects to record all sacred cantatas in historically informed performance were completed by Ton Koopman, John Eliot Gardiner, Pieter Jan Leusink[13] and Masaaki Suzuki.

[14] Sigiswald Kuijken began to record a cycle of cantatas for the Complete Liturgical Year with an OVPP choir and historic instruments, the ensemble La Petite Bande.