See Thomassin (Discipline de l'Eglise, tom. ii. 1. iii. e. 83, p. 176l-1770) and Bingham (Antiquities, vol. i. 1. xiv. c. 4, p. 688-717). Preaching was considered as the most important office of the bishop; but this function was sometimes intrusted to such presbyters as Chrysostom and Augustin.