The third precept (“You shall humbly receive your Creator in Holy Communion at least during the Easter season.") guarantees as a minimum the reception of the Lord's Body and Blood in connection with the Paschal feasts, the origin and center of the Christian liturgy. 84
Catechism number 2043
The fourth precept (“You shall keep holy the holy days of obligation.") completes the Sunday observance by participation in the principal liturgical feasts which honor the mysteries of the Lord, the Virgin Mary, and the saints.85