Strictly speaking, Holy Saturday belongs to the days when the Bridegroom was taken from us: the clergy on that day are not free either to celebrate or to receive Holy Communion.
The service of Holy Saturday is the great Easter vigil, or watch-service, held only in the late hours of the Saturday and barely terminating before midnight.
The consecration of the new fire with a view to the lighting of the lamps, the benediction of the paschal candle, with its suggestions of night turned into day and its reminder of the glories of that vigil which we know to have been already celebrated in the time of Constantine, the explicit references to "this most holy night" contained in the prayers and the Preface of the Mass, all bring home the congruity of carrying out the service in the late evening when Easter Vigil has begun.
The magnificent Praeconium Paschale, known from its first word as the Exsultet, was originally an improvisation of the deacon which can be traced back to the time of St. Jerome or earlier.
The Prophecies, the Blessing of the Font, and the Litanies of the Saints are all to be referred to a very essential feature of the Easter vigil, viz., the baptism of the catechumens, whose preparation had been carried on during Lent, emphasized at frequent intervals by the formal "scrutinies", of which not a few traces are still preserved in our Lenten liturgy.
Finally, the Mass, with its joyous Gloria, at which the bells are again rung, the uncovering of the veiled statues and pictures, the triumphant Alleluias, which mark nearly every step of the liturgy, proclaim the Resurrection as an accomplished fact, while the Lauds Office, incorporated in the very fabric of the Mass, introduces us to the consequences of the resurrection for all the Lord's faithful friends.