Here is instruction from Fr. Leonard Goffine, The Church’s Year.

What is Tenebrae, and what its meaning?

It is the office which the clergy say on Wednesday, Thursday, and Friday of this week, accompanied by the lamentations of the Prophet Jeremias, and other ceremonies. The word means darkness, and represents the prayers formerly said in the dark hours of the morning. In the Tenebrae the Church mourns the passion and death of, Jesus, and urges her children to return to God; she therefore makes use of those mournful words of Jeremias: “Jerusalem! Jerusalem, be converted to the Lord, thy God!”

Why is the Tenebrae said in the evening?

In memory of that time when the early Christians spent the whole night preceding great festivals in prayer, but later, when zeal diminished, it was observed only by the clergy on the eves of such festivals; also in order that we may consider the darkness, lasting for three hours, at the crucifixion of Christ, whence the name Tenebrae; and lastly, to represent by it that mourning, of which darkness is the type. 

Why, during the Prayers of the clergy, are the lights in the triangular candlestick extinguished one after another?

Because the Tenebrae, as has been already remarked, in the earliest times of the Church, were held in the night, the candles were extinguished one after another, as the daylight gradually approached they were no longer, necessary; again, at the time of the passion and death of Jesus, His apostles whom He calls the light of the world, one, after another gradually left Him; at the death of Christ the earth was covered with darkness. The Jews, blinded by pride, would not recognize Christ as the Saviour of the world, and therefore fell by His death into the deepest darkness of hardened infidelity.

What is meant by the last candle which is carried lighted behind the altar, and after prayers are finished, is brought back again?

This candle signifies Christ; who on the third day came forth from the grave, by His own power, as the true light of the world, though according to His human nature He died and lay in the grave until the third day.

Why is a noise made with clappers at the end of the Tenebrae?

This was formerly a sign that service was over; it, also signifies the earthquake which took place at Christ’s death.

How should we attend the Church service on this day?

The Church commemorates on this day the institution of the Most Blessed Sacrament of the Altar; we should therefore consider with a lively faith that Jesus, our divine Teacher and Saviour, is really and truly here present; we should adore Him as the Son of God, who became man to redeem us; should admire the love which determined Him to institute the Blessed Sacrament, that He might always be with us; and should thank Him for all the inestimable graces which we derive from this Sacrament.

On this and the two following days, the Church anticipates the Night-Office; she celebrates it on the previous evening of each day, and this in order that the Faithful may be present at it. The Matins and Lauds of Maundy Thursday are, therefore, said this afternoon. The Faithful should make every effort to assist at this solemn Office, seeing it is on their account that the Church has changed her usual hours. As to the merit there is in joining in it, there can be no doubt, but that it is to be preferred to any private devotions. The surest means for obtaining favours from God, and winning him to our requests, is to approach him through the Church. And as regards the feelings of devotion wherewith we ought to celebrate the mysteries of these three great Days, the Offices of the Church are, ordinarily speaking, a surer and richer source than the Exercises of Piety composed by men. The soul that feeds on the words and ceremonies of the holy Liturgy, will be all the more disposed to profit by the private devotions she practises at home. The prayer of the Church will thus become the basis, whereon is built the edifice of christian piety during these glorious Anniversaries of our Redemption; and we shall be imitating our forefathers who lived in the Ages of Faith, and who were such admirable Christians, because they lived the life of the Church, by means of the sacred Liturgy.

Dom proSper gueranger

RESOURCES:

The Office of Tenebrae booklets by Our Lady of Mt. Carmel, Littleton, CO. Click the image for the PDF download.

• Live Holy Thursday Tenebrae 2021 St. Mary’s on Broadway FSSP YouTube
• Holy Week in the Home — PDF with live links — Pre 1955 Holy Week Missal printables or DF to follow online, simple instructions, supplies needed for each day, and more!