With this antiphon, the Church proclaims Easter Sunday the greatest day of the year. For the Christian believer every day is, of course, a celebration of Jesus Christ's resurrection from the dead, as is every Mass. Yet daily rejoicing pales in comparison to that of the Sunday Mass, since Sunday is the day that the resurrection took place, the "eighth" day of the week signifying a new creation and a new life. And these Sundays of the year, in turn, are dwarfed by Easter, the Feast of Feasts celebrated in the newness of the vernal moon and in the rebirth of springtime.
Easter is the Christian day par excellence.
The commemoration of our Lord's physical resurrection from the dead provides not only the crucial resolution to the Passion story, but to several liturgical themes stretching back over the past two months.
Easter ends the seventy days of Babylonian exile begun on Septuagesima Sunday by restoring the Temple that was destroyed on Good Friday, i.e. the body of Jesus Christ.
It ends the forty days of wandering in the desert begun on Ash Wednesday by giving us the Promised Land of eternal life.
It ends the fourteen days of concealment and confusion during Passiontide by revealing the divinity of Jesus Christ and the meaning of His cryptic prophecies.
It ends the seven days of Holy Week by converting our sorrow over the crucifixion into our jubilance about the resurrection.
And it ends the three days of awesome mystery explored during the sacred Triduum by celebrating the central mystery of our faith: life born from death, ultimate good from unspeakable evil. It is for this reason that all the things that had been instituted at one point or another during the past penitential seasons (the purple vestments or the veiled images) are dramatically removed, while all the things that had been successively suppressed (the Alleluia, the Gloria in excelsis, several Gloria Patri's, or the bells) are dramatically restored.