BOB ABERNETHY: And now, the rediscovery of Celtic spirituality. When the pagan Celts of Ireland were converted to Christianity by St. Patrick in the 5th century, they brought with them their love of nature and friendship and their awareness of the sacred in all the most ordinary parts of life. Today, Celtic spirituality is resonating with more and more Americans, as Judy Valente reports from Chicago.

JUDY VALENTE: They are the quintessential images of Irish-American Catholicism, the bagpipers, the wearing of the green, the homage to St. Patrick who would convert the Celts of Ireland to Christianity in the 5th century. But this year, a few blocks off the parade route in Chicago, something different was happening. Bagpipes, yes, because this is Old St. Patrick's Church founded by Irish immigrants in the 19th century; its walls and ceiling adorned with art depicting the Irish Book of Cels, the 9th century illustrated gospel.

While the saint was being toasted elsewhere, people here were beginning the study of something different -- Celtic spirituality.

MR. JOHN O'DONOHUE (Theologian): I think the exciting thing in relation to Celtic spirituality is that a lot of American people are either of proximate or ultimate Celtic origin. And I think with the arrival of this, that they find in this something that is their own and they inhabit it and can dwell in it from within.

VALENTE: A nomadic tribe that first appeared in Eastern Europe hundreds of years before Christ, the Celts migrated westward, finally settling in the green fields of Ireland. The Celts were fierce warriors, but when they weren't at war they lived simple, agrarian lives. They found meaning in the most routine tasks of life, sacredness in the nature around them, and spiritual sustenance in the close ties of friendship, but they also valued solitude and silence.

This is the hushed, beautiful, and brooding landscape that was the Celtic environment.

MR. O'DONOHUE: I do believe the landscape has a huge influence on shaping the rhythm of mind and the shape of perception. The diversity of the Irish landscape, the amazing kind of lush that's in it -- there is something in the Irish landscape that naturally anchors a spirituality which somehow reveals or discloses the eternal. The Celtic spirituality had a wonderful recognition of nature as the theater of divine presence. That nature, in other words, wasn't an object, it wasn't matter, it was the place where the divine presence articulated its imagination and showed, in some sense, its rhythms and its beauty.

Unidentified Man: (Gaelic spoken)

VALENTE: The Gaelic tongue, language of the Celts, can still be heard in the rustic west of Ireland where John O'Donohue lives in a small cottage a mile from the nearest person.

MR. O'DONOHUE: (Gaelic spoken)

VALENTE: A scholar and poet, he visits this country to articulate the Celtic sense of wonder at the simple fact of creation.

MR. O'DONOHUE: I'd say the thing that I've never got over is the strange fact of being here on the planet at all. It's quite unbelievable to be on the Earth.

VALENTE: To the Celts, the circle symbolized the interconnectedness of everything; suffering and redemption, death, and resurrection. There were no hierarchies. Life was an unending circle with no beginning and no end.

MR. O'DONOHUE: So it never separated mind from body, soul from body, or God from us, or masculine from feminine, or nature from the divine, or time from eternity, but it had them all together within the one kind of circle.

VALENTE: In his writing, O'Donohue describes the Celtic view of close friendship as a way to find our own secret signature, our individuality, and our creativity.

Another person can be the mirror into our own souls. The community provides us with the gentle nest of belonging. But O'Donohue laments what he calls the "screaming loneliness" of modern life, the fragmentation of community.