From the Treasury of Daily Prayer:

The commemoration of Holy Saturday encompasses our Lord’s rest in the tomb and His descent into hell. The descent into hell is not, however, the depth of Christ’s humiliation but rather the demonstration of His complete victory over death. This day takes us out of the depths of most painful sorrow and out of the solitude of holy meditation upon Christ’s Passion to the celebration of victory as we anticipate the Lord’s resurrection breaking forth in all its glory on Easter.