20 We would wish this reflection on the origin and nature of those new and vital relationships which the Christian religion establishes between God and man to assume the character of an act of willing submission to what the divine Teacher said to those who listened to Him, and especially to the disciples, among whom we today rightly rejoice to be numbered. From the many insistent and frequently reiterated commands of Our Lord We select one which would seem to have special relevance for Christ's faithful followers at the present time, namely that concerning Christian vigilance.
Source: Ecclesiam Suam (Vatican.va)