Sixth Part: On Ecclesiastical Law

323. Ecclesiastical law is an ordination of human reason by which the Church and the baptized faithful are directed by him who has care of them unto sanctity and eternal life. For just as civil law is necessary for determining the natural law and for ruling the people in order to temporal felicity, so ecclesiastical law is necessary for determining, inculcating, completing, and urging by an added special sanction of penalty the natural and divine law, and thus for ruling the Christian people in order to the last end. It is not surprising, therefore, if many things said about human law are applied in the present matter.

1. St. Thomas does not specially treat ecclesiastical law, because this used to be done in the science of law.

The law is also called canonical, from the eighth century, from canons which are opposed to civil laws already in the Council of Ancyra (314) and Nicaea I (324); likewise sacred human law, both by reason of the authority which was constituted by Christ (by divine law), and by reason of the matter, which excludes temporal things as such, and by reason of the end, because it is made for the sanctification of souls. Hence it is a derivation, imitation, and supplement of divine law.