The Christmas cycle is centered round the birth of our Saviour; the Easter cycle is centered round his passion and Resurrection. In both, however, the theme is the same - the radical transformation of our lives by Christ's coming into this world. But whereas Christmas represents salvation coming from on high, the transformation of our life by the mystery of the Incarnation of the Word, Easter is salvation won by our Lord Jesus Christ's passion and death. Christmas means the coming of our Saviour-already we experience the joy of being saved, since our Saviour has come among us. Easter means our Lord in conflict with the devil and the powers of evil from which he issues triumphant, crushing Satan and rising in glory taking us in his wake to our heavenly home; Easter means the redemption of man obtained at the price of the cross.
The liturgical season which begins with Septuagesima and continues until the end of Lent is marked as a period of struggle and toil which we must undergo with Christ, leading, by his grace, to the victory and triumphant joy of Easter. On the days after Easter comes the gladness of the baptized raised up with Christ to a new life. Taken as a whole the Easter cycle puts before us the most fundamental and striking aspect of our life: men's sin and weakness expiated and mastered by Christ's redemption. It reminds us that Christ came to us as our Redeemer; we need redemption. And it is as the redeemed that our real realtionship with God is to be found; the felix culpa of the Easter vigil has no other meaning than the overflowing joy of the redeemed who exult in their redemption.
(St. Andrew Missal)