The phrase Celtic Rite must not be taken to imply any necessary homogeneity, notes the Catholic Encyclopedia. For the evidence such as it is, is in favor of considerable diversity. Far from an insular religion, Irish Catholicism spread to France, Germany, Switzerland, Italy, and Northern Spain through the missions of St. Columbanus and others, and both influenced and absorbed the Continent's practices throughout the medieval period.

Historians have recently set out to restore [the Irish Church] to its rightful place on the European historical map, writes Trinity College Dublin's Ann Buckley in her introduction to a book of scholarly essays called Music, Liturgy, and the Veneration of Saints of the Medieval Irish Church in a European Context.

To varying degrees, all of the scholars represented in this collection write to counter the essentializing quest for what might be unique or other about Ireland and Irish culture" among all other European national and religious histories.

Buckley's writing on the veneration of Irish saints has made a significant contribution to this effort, and her decade and a half of archival work has helped create the Amra project, which aims to digitize and make freely available online over 300 manuscripts containing liturgical material associated with some 40 Irish saints which are located in research libraries across Europe.