TWELVE MILES FROM THE ocean, near the town of Dover, New Hampshire, the Salmon Falls and Cocheco rivers combine to give birth to the mighty Piscataqua River..

The Pis-CAT-a-qua, as the locals say it, flows rapidly. Its wide tidal estuary floats beneath the green painted steel struts of the Piscataqua River Bridge, which cantilevers the six lanes of Interstate 95 across the river from south to north. It flows beneath the Sarah Mildred Long Bridge that carries US Route 1, and past the Memorial Bridge, now being replaced, which links Portsmouth, New Hampshire, with Kittery, Maine. Here in Kittery, settled by the Shapleighs and the Chadbournes in 1623, the river waters flow around the Los Angeles-class nuclear submarines being retrofitted at the Portsmouth Naval Shipyard, before emptying, finally, into the sea.

Halfway along the Piscataqua’s route, six miles from the ocean, a three-story hotel stands in Colonial Revival style on a plateau sixty feet above the river’s north bank, among twenty-three acres of rolling meadow in Eliot, Maine. About a dozen other structures rest nearby: lodging houses, offices, a library and archives, and a conference center. The place is called Green Acre.

In 1912, a flagpole made from two ship’s masts rose from the grounds to a height of eighty-five feet. It flew a white flag, thirty-six feet wide, the word “PEACE” emblazoned across it in large green letters. ‘Abdu’l-Bahá could see it from the seat of his automobile. He had left Dublin, New Hampshire, at 10 a.m. on Friday, August 16, 1912, with three of his secretaries and Mr. Alfred Lunt, a New England lawyer. The party stopped for lunch in Nashua, arriving in Eliot in the afternoon. At last the car descended from the main road to the Inn on the river, over a long driveway that had been dressed on both sides with a thousand multicolored Japanese lanterns. Five hundred people waited to receive ‘Abdu’l-Bahá.

Green Acre had been founded by Sarah J. Farmer in 1894. Her intention: to place the 1893 World’s Parliament of Religions on a permanent basis. The Green Acre forum soon became a flourishing center of thought, where Hindu swamis, Iranian scholars, social Darwinists, New Thought advocates, Japanese artists, electrical engineers, opera singers, social reformers, and the last of the Transcendentalists gathered each summer. At Green Acre thousands of New Englanders — guided by Sarah Farmer’s vision of the practical role of religion and spirituality in a rapidly modernizing America — first learned to converse with the brimming intellectual, cultural, and religious diversity that Americans were beginning to encounter as they took their first tentative steps as a nation onto the international stage.

Leigh Eric Schmidt, an American historian of religion, describes how Sarah Farmer’s forum on the Piscataqua’s northern bank became a crossroads for many of the spiritual quests that characterized America at the turn of the century. In his 2005 book, Restless Souls: The Making of American Spirituality, Schmidt argues that “Green Acre was among the greatest sources of religious innovation anywhere in the country.”

“It was the last great bastion of Transcendentalism, a school of philosophy and art for Emersonians and Whitmanites; it was a New Thought proving ground for such leaders as Ralph Waldo Trine, Henry Wood, and Horatio Dresser; it was a hub for representatives of the Society of Ethical Culture, Theosophy, Buddhism, Reform Judaism, Vedanta, Zoroastrianism, Islam, and the Bahá’í Faith. It was the World’s Parliament of Religions brought to its grandest fruition, attracting the curious and the questing . . . by the hundreds and even thousands in these years.”

“At Greenacre,” Schmidt writes, “the dream of a cosmopolitan spirituality found its flesh and blood.”