That Whitsunday belongs to the Apostolic times is stated in the seventh of the (interpolated) fragments attributed to St. Irenæus. In Tertullian (On Baptism 19) the festival appears as already well established. The Gallic pilgrim gives a detailed account of the solemn manner in which it was observed at Jerusalem ("Peregrin. Silviæ", ed. Geyer, iv). The Apostolic Constitutions (Book V, Part 20) say that Pentecost lasts one week, but in the West it was not kept with an octave until at quite a late date. It appears from Berno of Reichenau (d. 1048) that it was a debatable point in his time whether Whitsunday ought to have an octave. At present it is of equal rank with Easter Sunday. During the vigil formerly the catechumens who remained from Easter were baptized, consequently the ceremonies on Saturday are similar to those on Holy Saturday.
The office of Pentecost has only one Nocturn during the entire week. At Terce the "Veni Creator" is sung instead of the usual hymn, because at the third hour the Holy Ghost descended. The Mass has a Sequence, "Veni Sancte Spiritus" the authorship of which by some is ascribed to King Robert of France. The colour of the vestments is red, symbolic of the love of the Holy Ghost or of the tongues of fire. Formerly the law courts did not sit during the entire week, and servile work was forbidden. A Council of Constance (1094) limited this prohibition to the first three days of the week. The Sabbath rest of Tuesday was abolished in 1771, and in many missionary territories also that of Monday; the latter was abrogated for the entire Church by Pius X in 1911. Still, as at Easter, the liturgical rank of Monday and Tuesday of Pentecost week is a Double of the First Class.In Italy it was customary to scatter rose leaves from the ceiling of the churches to recall the miracle of the fiery tongues; hence in Sicily and elsewhere in Italy Whitsunday is called Pascha rosatum.
The Italian name Pascha rossa comes from the red colours of the vestments used on Whitsunday. In France it was customary to blow trumpets during Divine service, to recall the sound of the mighty wind which accompanied the Descent of the Holy Ghost. In England the gentry amused themselves with horse races. The Whitsun Ales or merrymakings are almost wholly obsolete in England. At these ales the Whitsun plays were performed. At Vespers of Pentecost in the Oriental Churches the extraordinary service of genuflexion, accompanied by long poetical prayers and psalms, takes place. (Cf. Maltzew, "Fasten-und Blumen Triodion", p. 898 where the entire Greco-Russian service is given; cf. also Baumstark, "Jacobit. Fest brevier", p. 255.) On Pentecost the Russians carry flowers and green branches in their hands.