Dies Domini is an apostolic letter promulgated by Pope John Paul II on July 30, 1998. In this doctrine, Pope John Paul encourages the Catholic population to 'rediscover the meaning' behind keeping the Lord's Day holy. Pope John Paul II explains the meaning of the Sunday in the light of Christian tradition. To celebrate Sunday is to make present the graces of the Paschal mystery, which is the climax of the salvation history: — Dies Domini, 18