In Cat. xv. there is no note of time to determine on what day it was spoken; but in § 33 Cyril speaks as if his course of teaching was to be interrupted for a little while:  “If the grace of God should permit us, the remaining Articles also of the Faith shall be in good time (κατὰ καιρόν) declared to you.”  We may therefore assign Cat. xv. to the early part of Passion week, and the three remaining Catechetical Lectures to the week before Easter.  This arrangement seems to be confirmed by Cat. xvii. 34, where Cyril speaks of the two Lectures on the Holy Spirit, xvi. and xvii., as “these present Lectures,” distinguishing them from “our previous discourses.”  In the same section he refers to “the fewness of the days,” and in § 20 speaks of “the holy festival of the Passover” as being close at hand.  We may therefore probably assign xvi. and xvii. to two consecutive days in the earlier part of the week before Easter.