[16] Lay-baptism in view of imminent death is a practice as old as the Christian Church. The right of the laity to administer baptism in such cases was expressly recognized by the Council of Elvira, in the year 306, and the decree of that Council became a part of the law of the Church. The right of the laity to give absolution in such cases rests on the principle that in the absence of the appointed official of the Church any Christian can do for any other Christian the things that are absolutely necessary or salvation, for "necessity knows no law." Cf. Vol. I, p. 30, note 2. [17] The canon law, called by Luther throughout this treatise and elsewhere, the "spiritual law," is a general name for the decrees of councils ("canons" in the strict sense) and decisions of the popes ("decretals," "constitutions," etc.), promulgated by authority of the popes, and collected in the so-called _Corpus juris canonici_. It comprised the whole body of Church law, and embodied in legal forms the mediæval theory of papal absolutism, which accounts for the bitterness with which Luther speaks of it, especially in this treatise. The Corpus includes the following collections of canons and decretals: The _Decretum of Gratian_ (1142), the _Liber Extra_ (1234), the _Liber Sextus_ (1298), the _Constitutiones Clementinae_ (1318 or 1317), and the two books of _Extravagantes_ ,--the _Extravagantes of John XXII_, and the _Extravagantes communes_. The last pope whose decrees are included is Sixtus IV (died 1484). See _Catholic Encyclop._,IV, pp. 391 ff. [18] Augustine, the master-theologian of the Ancient Church, bishop of Hippo in Africa from 395-430. [19] Ambrose, bishop of Milan from 374-397, had not yet been baptised at the time of his election to the episcopate, which was forced upon him by the unanimous voice of the people of the city. [20] Cyprian, bishop of Carthage, 247-258, is said to have consented to accept the office only when the congregation surrounded his house and besought him to yield to their entreaties. [21] _Was ausz der Tauff krochen ist_.