Tantum Ergo (404.Organ) Tantum ergo Sacramentum (Therefore so great a Sacrament). Saint Saens wrote two settings of this music, this one being unpublished without an opus number. It is a short liturgical piece he wrote in 1860 while working as a young church organist at LEglise da la Madeleine. The music, originally written for 2 sopranos, alto, organ and optional chorus is very simple in nature with a religious and atmospheric feel to it. Mr. Couturier has done a wonderful job arranging this 4-minute work for 8-part Brass Ensemble of moderately advanced performers.