Here he begins to define the sacraments in general, and it is divided into two parts: in the first, he defines the sacraments in themselves; in the second, he divides the sacraments into their parts, at: a sacrament consists of two elements.
Prima in duas: in prima ostendit quid est sacramentum; in secunda necessitatem institutionis sacramentorum, ibi, triplici autem ex causa sacramenta instituta sunt.