The proper Offices and Masses celebrated during Holy Week do not notably differ from the Office and Mass at other penitential seasons and during Passion Week. But it has long been customary in all churches to sing Matins and Lauds at an hour of the afternoon or evening of the previous day at which it was possible for all the faithful to be present. The Office in itself presents a very primitive type in which hymns and certain supplementary formulae are not included, but the most conspicuous external feature of the service, apart from the distinctive and very beautiful chant to which the Lamentations of Jeremias are sung as lessons, is the gradual extinction of the fifteen candles in the "Tenebrae hearse", or triangular candlestick, as the service proceeds. At the end of the Benedictus at Lauds only the topmost candle, considered to be typical of Jesus Christ, remains alight, and this is then taken down and hidden behind the altar while the final Miserere and collect are said. At the conclusion, after a loud noise emblematical of the convulsion of nature at the death of Christ, the candle is restored to its place, and the congregation disperse. On account of the gradual darkening, the service, since the ninth century or earlier, has been known as "Tenebrae" (darkness). Tenebræ is sung on the evening of the Wednesday, Thursday, and Friday, the antiphons and proper lessons varying each day.