Only four canonised saints
Only four saints, St Malachy (1094-1148), St Lawrence O'Toole (1128-80) and St Oliver Plunkett (1625-81) and St Charles of Mount Argus (1821-93), have been officially canonised. All the other Irish saints, such as Saints Patrick, Brigid, and Colmcille, are saints, as it were, by acclamation of the local Church.
Canonisation
"Canonisation" as a process can be said to have begun when the name of a martyr was included in the dyptichs (or prayer lists) proclaimed by the deacon during Mass. This process would have been overseen by the local Church authority, especially the bishop. Later the names of holy people who were not martyrs, such as Saint Hilarion and Saint Ephrem the Syrian in the East, and Saint Martin of Tours and Saint Hilary of Poitiers in the West, were included. But it was only in 1170 that Alexander III issued a decree arrogating to the Pope alone the right to declare a person a saint as regards the Church of the West. This was confirmed in 1200 by a bull of Pope Innocent III.
The scope of the feast
The scope of this feast, while it includes canonised saints, is wider. It also includes those who had a reputation for holiness and whose causes for canonisation have not yet been completed, such as Blessed Thaddeus MacCarthy (1455-92), the seventeen Irish martyrs of the 16th and 17th centuries, Blessed Edmund Ignatius Rice (1762-1844), Blessed Columba Marmion (1858-1923) and the Servant of God [now Venerable] Matt Talbot (1856-1925) and people like Legion of Mary envoys Edel Quinn and Alfie Lamb, whose causes have already been introduced. But it also includes those whose lives of sanctity were known only to their families, friends or members of their parish diocese or religious community.
An exchange of spiritual goods
Like All Saints (1 Nov) and All Souls (2 Nov), this is a celebration of the communio sanctorum, that is, a sharing, not only of the "holy persons" (sancti and sanctae), but also of the "holy things" (sancta). As the Dogmatic Constitution Lumen Gentium on the Church of Vatican II taught:
"So it is that the union of the wayfarers with the brethern who sleep in the peace of Christ is in no way interrupted, but on the contrary, according to the constant faith of the Church, this union is reinforced by an exchange of spiritual goods" (LG 49).
Island of Saints and Scholars
The reading from the Book of Ecclesiasticus 44:1-15 echoes the theme of "the island of saints and scholars" which was so strong in Ireland in the first half of the twentieth century.
Let us praise illustrious men,
our ancestors in their successive generations.
The Lord has created an abundance of glory,
and displayed his greatness from earliest times.
Source: http://www.catholicireland.net/pages/index.php?art=1887
Note: For a listing of and information about Irish saints, click http://www.catholic.org/saints/irish.php