November 4 was the fourth anniversary of Pope John XXIII's incoronation as Pope. A Mass to celebrate this anniversary was celebrated by Cardinal Montini, future Pope Paul VI. The Mass was celebrated in the Ambrosian Rite proper to the Archdiocese of Milan.
At the Mass, after beginning his homily in Latin, the Pope switched to Italian in order be “better understood” and said:
It is quite natural that the newness of times and circumstances suggest diverse forms and attitudes of exteriorly tranmitting the same truth and of giving it a new clothing.
Thus, the Pope reiterated a principle crucial to understanding the Council as a whole: aggiornamento, an Italian word meaning a “bringing up to date.” Aggiornamento was used to mean a spirit of change and open-mindedness to contemporary world realities.