Editing Trinity Sunday (section)

===History===
In the early Church, no special Office or day was assigned for the Holy Trinity. When [[Arianism|the Arian heresy]] was spreading, the Fathers prepared an Office with canticles, responses, a Preface, and hymns, to be recited on Sundays. In the Sacramentary of [[Pope Gregory I|Gregory the Great]] there are prayers and the Preface of the Trinity. During the Middle Ages, especially during the [[Carolingian Renaissance|Carolingian period]], devotion to the Blessed Trinity was a highly important feature of private devotion and inspired several liturgical expressions.<ref name="directory">{{Cite web |title=Library : Directory on Popular Piety and the Liturgy: Principles and Guidelines |url=http://www.catholicculture.org/culture/library/view.cfm?recnum=4620 |access-date=2019-11-30 |website=www.catholicculture.org}}</ref> Sundays are traditionally dedicated to the Holy Trinity.<ref name="Kosloski2019" />

The [[wikt:micrology|Micrologies]] written during the pontificate of [[Pope Gregory VII|Gregory VII]] list no special Office for the Sunday after Pentecost, but add that in some places they recited the Office of the Holy Trinity composed by Bishop [[Stephen of Liège]] (903–920). By others the Office was said on the Sunday before Advent. [[Pope Alexander II|Alexander II]] (1061–1073), refused a petition for a special feast on the grounds that such a feast was not customary in the Roman Church which daily honoured the Holy Trinity by the ''[[Gloria Patri]]'', etc., but he did not forbid the celebration where it already existed. A new Office had been made by the Franciscan [[John Peckham]], Canon of Lyons, later Archbishop of Canterbury (d. 1292).<ref name="mershman" />

[[Pope John XXII|John XXII]] (1316–1334) ordered the feast for the entire Church on the first Sunday after Pentecost and established it as a Double of the Second Class.<ref name="mershman" /> It was raised to the dignity of a primary of the first class, 24 July 1911, by [[Pope Pius X]] (Acta Ap. Sedis, III, 351). Since it was after the first great Pentecost that the doctrine of the Trinity was proclaimed to the world, the feast becomingly follows that of Pentecost.