The Triduum (from the Latin meaning three days) is often referred to as The Three Great Days – Maundy Thursday- Good Friday- Easter Vigil.
According to this tradition there is a difference in the way we enter into the spirituality of Triduum and that of Easter Day. As we observe the Triduum we enter into the Paschal Mystery in which the passion-death-resurrection of Jesus Christ saves and redeems us. Easter Day is a celebration of utter joy and introduces the 50 days of Easter celebration.
The Triduum is therefore a single, unitary celebration of the whole Paschal Mystery. It is not merely an historical rehearsal of a sequence of three events over three succeeding days but is a solemn entering into the saving mystery of the passion- death-resurrection-event in the life of Jesus. That is one event- we do not enter into Good Friday as those who do not know how this will end, and we do not enter into the resurrection as those who do not know where it began and how we got here. That is why there is this essential unity to The Three Days which is expressed in the fact that there is only one beginning and one ending to the liturgy of the Triduum.
The unity if this single celebration is clearly shown in the structure of the services. There is a Greeting at the start of the Maundy Thursday Eucharist, but no dismissal; no formal beginning or dismissal at the Good Friday devotions, and no greeting at the Service of Light that starts the Great Vigil of Easter. It is only at the end of the Vigil Service that the congregation join in the joyful dismissal that sends people out to love and serve the Lord with a great cry of ‘Alleluia! Alleluia!’
In this single service we gather together to celebrate the complete drama of salvation into which we are invited. It is a gathering that celebrates the new commandment to love and serve one another, revealed by a Lord who washes the feet of the disciples, including Judas who betrayed Him, and Peter who denied Him, all played out in the context of the joyful celebration of the liberation of the people of God from the oppression of slavery in Egypt; it is a gathering of the people of God at the Cross as those who know the truth of the victory of our Lord over darkness, sin and rejection; a gathering of the people who join together to celebrate the resurrection of the Lord as those who have kept watch through His passion and greet Him with joy on Easter morning.
Each part needs to be planned carefully since the proclamation will be carried as much by the liturgy as by the preached word, and each part must be planned as part of the whole.