Thomas Aquinas Quote

The apostles and their successors are God's vicars in governing the Church which is built on faith and the sacraments of faith. Wherefore, just as they may not institute another Church, so neither may they deliver another faith, nor institute other sacraments.

The "Summa Theologica: 1. QQ.I-XXVI. Treatise on the incarnation (ed. 1914)