26. By contrast, the Sabbath’s position as the seventh day of the week suggests for the Lord’s Day a complementary symbolism, much loved by the Fathers. Sunday is not only the first day, it is also “the eighth day”, set within the sevenfold succession of days in a unique and transcendent position which evokes not only the beginning of time but also its end in “the age to come”. Saint Basil explains that Sunday symbolizes thatCwhich will follow the present time, the day without end which will know neither evening nor morning, the imperishable age which will never grow old; Sunday is the ceaseless foretelling of life without end which renews the hope of Christians and encourages them on their way. Looking towards the last day, which fulfils completely the eschatological symbolism of the Sabbath, Saint Augustine concludes the Confessions describing the Eschaton as “the peace of quietness, the peace of the Sabbath, a peace with no evening”. In celebrating Sunday, both the “first” and the “eighth” day, the Christian is led towards the goal of eternal life.
lettre Apostolique de saint Jean Paul II- 31 mai 1998