Fourth Part: On the Cause of the Sacraments

67. Matter to be treated. - To cause a sacrament is not simply to determine the sacramental sign, or the matter and form, but is to give to them the power of signifying and effecting; and this can be done in two ways: 1. by authority, i.e., as principal efficient cause, by a power proper to oneself and not derived from another superior; 2. by ministry, i.e., as instrumental cause, or by a power derived from a superior, which again is twofold: a) principal ministerial, which has a certain principality with respect to other instruments, and b) simply ministerial, which is immediately ministering.

Moreover, any kind of power whatever can be considered either in the institution or in the dispensation of the sacraments. Besides, for the existence of a sacrament there is required a subject capable of reception, which is the material cause. Hence we shall speak: 1. of the instituting cause, 2. of the ministering cause, 3. of the receiving cause.