Born in 521, he was educated at the monastery of St. Finnian in Clonard in Co. Meath. When he returned home, he founded churches and monasteries. A man of letters, he got involved in a copyright dispute. He borrowed the Book of Psalms from St. Finnian and made a copy of it.  Finnian claimed the copy as his own. Brought for resolution, Finnian won. A battle ensued. Subsequently Colmcille decided to leave Ireland.

He went to Iona, with twelve followers, in 563, where he established a monastery. From there missionaries went to other parts of Scotland, and to northern England, to bring the good news of Jesus.

Colmcille died in Iona in 597.

A prayer attributed to St. Colmcille

Lord, you are my island; in your bosom I rest.

You are the calm of the sea; in that peace I stay.

You are the deep waves of the shining ocean; with their eternal sound I sing.

You are the song of the birds; in that tune is my joy.

You are the smooth white strand of the shore; in you is no gloom.

You are the breaking of the waves on the rock; Your praise is echoed in the swell.

You are the Lord of my life.