Concerning the first point he does two things: first, he places the sacrament in the genus of signs; second, he defines signs, at A sign is a thing which, over and above the form which it impresses on the senses, causes something else to come into the mind through itself.
Prima in duas: in prima ostendit quid est sacramentum; in secunda necessitatem institutionis sacramentorum, ibi, triplici autem ex causa sacramenta instituta sunt.