'This world is not my home/I'm just a passin' through". So ran an old hymn. Early Christianity emphasised the need to welcome all exiles, for they just might turn out to be a chosen people. This was its truly radical innovation: that there were no longer Jews or Greeks, slaves nor freemen, writes Declan Kiberd
There were to be no more foreigners: "For you are all one in Jesus Christ." Jesus was that ultimate nomad, a wanderer with "no place to lay his head".
The underlying idea has been repeated for crudely commercial reasons in our own times by Ted Turner when he banned the use of the word "foreigner" on CNN News. For there are no strangers in Televisionland - only fellow consumers who haven't yet met.
What was most romantic in Christianity was its openness to the stranger. "Love him as yourself", the book of Leviticus had enjoined well before Jesus repeated the line, "for you were once strangers in Egypt".
The history of the Irish, themselves dispossessed for centuries, yet for all that secure in a communal identity, seemed to bear out this idea of a people nation open to perpetual joiners. The Normans became more Irish than the Irish themselves - and now it's the turn of the Nigerians, the Poles, the Chinese. Or is it?
Somehow, current Irish writing - and maybe current writing in other lands too - hasn't quite managed to register the romance and audacity of the idea of a world without foreigners and strangers.
A few days ago, I read the closing episodes of Joyce's Ulysseswith a group of very alert students, mostly Irish, some American, and one or two continental Europeans. We talked of the climatic meeting between Stephen Dedalus, a young poet, and Leopold Bloom, an older man and small-ad canvasser.
One student described Bloom's offer of coffee and a bun to the hungry youth as a "sort of ironic Eucharist". "Ironic" was a good word, given that earlier in the book Bloom had joked about the communicants at the Roman Catholic altar rails: "Good idea the Latin. Stupefies them first." There spoke the ad man (amused by the effective jingle), as well as the social anthropologist.
"Yes," I countered, "but can I ask you all a harder question? If, say, tomorrow, a strange Jewish man, in his late 30s, bumped into you well after midnight in one of the seedier coffee bars in Dublin and invited you back to his house to sleep off your hangover, would you go with him?" They all smiled a little sadly and shook heads. Definitely not.
Yet Joyce celebrates a civic city precisely because its mode of circulation made such unexpected meetings possible.
Today, that city is very different. Today, most socialising is "horizontal" - Poles meet Poles in special areas; Mount Anville girls meet Blackrock College boys at designated discos; young people seldom start up conversations with older men in bars, because these days each bar is becoming more and more age specific.
All this may help to explain a surprising fact first noted by my student, Zeljka Doljanin, a young Croatian mother who has lived here for some years and is writing a brilliant thesis on the treatment of the "stranger" in current Irish fiction. Her findings are stark.
With a few honourable exceptions, such as Roddy Doyle, Clare Keegan, Joe O'Connor and others, she sees our younger fictionists preferring to write safely about their own set rather than encounters with the "other".
It wasn't always so. The classics of Irish writing, from Gulliver's Travelsthrough Castle Rackrentdown to Ulysses, read like a crash course in how people, by embracing the "stranger" outside themselves, also come to terms with the "stranger" within themselves. "Even the monocultural world of McGahern has far more treatments of the 'other'," Ms Doljanin said to me one day.
I asked McGahern, just before he died, whether he thought her thesis was true. He nodded. "In Leitrim in the 1940s, if you travelled 10 miles on a bicycle, you were in a foreign country. The people's very way of walking, of moving their bodies, of using words - they were all strangely different."
McGahern said that this prepared you better for the strangeness that was the rest of the universe - rather better, perhaps, than those well-meaning posters which "celebrate diversity" with a monotonous intensity that may arise from the fear that we are all - Leitrim folk, Dubs, Poles, Africans - becoming more and more similar. What Gertrude Stein once said of Oakland - "there's no there there any more" - may now be true of Ireland.
But, still, there's something a little weird about all this, isn't there? We have tens of thousands of immigrants among us for the first time in history, yet they seem all but invisible in our contemporary literature.
Maybe it will take thoughtful writers a few more years yet to work them into the script?