"Do you not know that all of us who have been baptized into Christ Jesus were baptized into His death? We were buried with Him therefore by baptism into death, so that as Christ was raised from the dead,...we too might walk in newness of life." Simply put, baptism is our death and resurrection in Christ--not merely in symbol or figure, but in reality. The "old man"--our self-centered ego--is put to death. Truly it ceases to exist! Thus--having put on Christ--death is transformed into life through the power of our Lord's glorious Resurrection.
Today is the blessed Sabbath, whereon Christ rested from His redemptive work. As the priest says while censing the Altar Table before every Divine Liturgy, "In the tomb with the body, in hell with the soul, in paradise with the thief, and on the Throne with the Father and the Holy Spirit..." Thus, even while our Lord's body lies in the tomb awaiting His Resurrection on the third day, His soul descends into Hades, where He tramples down death by death.
And so....Just as death is transformed into life, so is the profound sorrow of Holy Friday transformed into joy. Thus, while it is inevitable that our bodies must die and be laid to rest in the earth, the seeds of resurrection have already been implanted--and truly we shall rise again on the Last Day to eternal life in God's heavenly Kingdom.
Likewise, though our earthly sojourn is a time of sorrow, the seeds of joy implanted in our souls even now blossom forth at unexpected moments. Thus we experience what the Holy Fathers term "joyful sorrow"--which is a foretaste of that eternal joy that awaits all who love Christ and strive at all times to do His will.