"Watch, therefore, for you do not know on what day your Lord is coming" (Mt 24: 42). Jesus, who came among us at Christmas and will return in glory at the end of time, does not tire of visiting us continuously in everyday events. He asks us to be alert to perceive his presence, his advent, and recommends that we watch and wait for him since his coming is not programmed or foretold but will be sudden and unexpected. Only those who are alert are not taken by surprise. He warns: may it not happen to you as in Noah's day, when men ate and drank heedlessly and were swept away unprepared by the flood (cf. Mt 24: 37-38). What does the Lord want to make us understand with this warning, other than we must not let ourselves be absorbed by material realities and concerns to the point of being ensnared by them? We must live in the eyes of the Lord with the conviction that he can make himself present. If we live in this way, the world will become better. 

"Watch, therefore". Let us listen to Jesus' Gospel invitation and prepare ourselves to relive with faith the mystery of the Redeemer's birth, which filled all the world with joy; let us prepare ourselves to welcome the Lord in his constant coming to us in the events of life, in joy and in pain, in health and in sickness; let us prepare ourselves to meet him at his definitive coming. His nearness is always a source of peace, and if suffering, a legacy of human nature, sometimes becomes unbearable, with the Saviour's advent "suffering - without ceasing to be suffering - becomes, despite everything, a hymn of praise" (Spe Salvi, n. 37).

[Pope Benedict, homily at the Roman hospital of St. John the Baptist, 2 December 2007]