Günter Raphael (1903-1960) studied in music in Berlin and became teacher for counterpoint and theory in Leipzig. As his father was Jewish he was not allowed to work during the Nazi regime. 1957 he became Professor at the Cologne School of Music. For further information see http://www.guenter-raphael.de
(information in German and English).
In this short choral prelude Raphael treats the melody as a canon in the lower fifth between soprano and alto. BTW, this works rather well in a mean-tone temperament.