Zachow wrote a four part fugato on the first phrase of the chorale melody of "Wir glauben all' an einen Gott". Though each voice plays the fugato theme two or three times, the four voices seldom play all four at the same time. So you could say that Zachow cheated a little in writing this four part fugato. It is nevertheless a fine piece. As the music has something tender and vulnerable I played on just the Vox Humana of the Bovenwerk of this organ.
The recording was done with the Hauptwerk software and the demo sampleset, made by Sonus Paradisi, of the Schnittger organ in the St Martinikerk, Groningen