For an American tourist weaned on Gaelic kitsch and screenings of “The Quiet Man,” the landscape of contemporary Ireland comes as something of a shock. Drive from Dublin to the western coast and back, as I did two months ago, and you’ll still find all the thatched-roof farmhouses, winding stone walls and placid sheep that the postcards would lead you to expect. But round every green hill, there’s a swath of miniature McMansions. Past every tumble-down castle, a cascade of condominiums. In sleepy fishing villages that date to the days of Grace O’Malley, Ireland’s Pirate Queen (she was the Sarah Palin of the 16th century), half the houses look the part  but the rest could have been thrown up by the Toll brothers.

It’s as if there were only two eras in Irish history: the Middle Ages and the housing bubble.

This actually isn’t a bad way of thinking about Ireland’s 20th century. The island spent decade after decade isolated, premodern and rural  and then in just a few short years, boom, modernity! The Irish sometimes say that their 1960s didn’t happen until the 1990s, when secularization and the sexual revolution finally began in earnest in what had been one of the most conservative and Catholic countries in the world. But Ireland caught up fast: the kind of social and economic change that took 50 years or more in many places was compressed into a single revolutionary burst.

There was a time, not so very long ago, when everyone wanted to take credit for this transformation. Free-market conservatives hailed Ireland’s rapid growth as an example of the miracles that free trade, tax cuts and deregulation can accomplish. (In 1990, Ireland ranked near the bottom of European Union nations in G.D.P. per capita. In 2005, it ranked second.)