A grave obligation of Catholics to assist at Mass on all Sundays and holy days of obligation. As expressed by the Second Vatican Council, referring to Mass on Sunday, "On this day the faithful are bound to come together into one place. They should listen to the word of God and take part in the Eucharist, thus calling to mind the Passion, Resurrection and glory of the Lord Jesus Christ" (Constitution on the Liturgy, V, 106). The imperatives "are bound to come together" indicates the gravity of the obligation, which according to the Church's tradition, affects all baptized persons who have reached the age of reason. They are obliged under penalty of serious sin to hear Mass on Sundays and holy days, which means that the duty is objectively serious. Subjectively the gravity of the sin will depend on excusing circumstances, notably a person's awareness of the dignity and necessity of the Eucharistic Sacrifice.