On Thursday, Friday and Saturday mornings Matins and Lauds are always said together, and these three services are commonly called the Three Nights of Darkness. In the choir six lights are lighted upon the Altar, and fifteen (seven on each side and one at the top) in a triangle-shaped candlestick before the Epistle corner. As each Antiphon is repeated the second time, one of the fifteen candles is extinguished.
As the Antiphon “Now he that betrayed Him etc.” is repeated the second time, the candle at the top of the triangular candlestick is taken and hidden behind the Altar, at the Epistle corner.
When all the prayers are over some noise is made, the hidden light is put back on the triangular candlestick, and all present immediately rise and depart in silence.