from the INTRODUCTION: Islands are everywhere. There are islands in the middle of a lake, some sacred--such as Manitoulin in Lake Huron, the largest freshwater island in the world, or Isla del Sol, one of the forty or so islands in Lake Titicaca--and some sentimental, such as William Butler Yeats''s Lake Isle of Innisfree or Jean-Jacques Rousseau''s St. Peter''s Island in Switzerland''s Lake Biel; others are dear to the hearts of those who live in or visit the lake regions of the world. There are islands in rivers and streams, some supporting great cities, like New York and Montreal, others shaping cultures, like Île de la Cité in Paris, and still others whose influence seems more modest, like the "smallest, barest island" in New England''s Merrimack River, which Henry David Thoreau described as having an "undefined and mysterious charm." There are islands in between, such as the Canaries and the Azores, the Hebrides and the Faroes--those so-called stepping-stone islands in the Atlantic that offered relatively safe haven to early seafarers--or the chain of outcrops called Rama''s Bridge (or Adam''s Bridge) that links Sri Lanka to the mainland. There are islands in the deltas of the great rivers of Asia and Africa, like the Irrawaddy and the Zambezi, and islands where land and water are confused, like the muskeg islands at the edge of the boreal forest in Canada or the Sundarbans, the mangrove swamps in the Ganges Delta (which, according to one nineteenth-century observer, "looked as though this bit of world had been left unfinished when land and sea were originally parted"). While many islands are out on the open ocean, all alone and far away from any other land--such as Tristan da Cunha in the South Atlantic and Easter Island in the Pacific--others are snuggled along the shore, like Haida Gwaii on Canada''s west coast, Australia''s Great Barrier Reef, and the islands that shape Singapore and Hong Kong, Mumbai and Venice. Countless rock outcrops and coral atolls are uninhabited by humans, while large islands like Java and Japan have a population of over a hundred million each.

Altogether, about one billion people live on islands. They are often fiercely (if sometimes foolishly) independent. Nearly one quarter of the members of the United Nations are island nations, some of them as small as Nauru (once called the Pleasant Island) or Tuvalu (formerly known as the Ellice Islands) in the Pacific, each under ten square miles in total and with populations around ten thousand. Eleven of the world''s fifteen smallest countries are islands, including the Seychelles and the Maldives in the Indian Ocean, Malta in the Mediterranean, and several island nations in the Caribbean: Saint Kitts and Nevis; Grenada; Saint Vincent and the Grenadines; Antigua and Barbuda; and Barbados. (Their only mainland rivals for size are Vatican City, Monaco, San Marino, and Liechtenstein.) There are islands that limit us, and islands that liberate us; islands where love flourishes, and islands where hatred takes root; islands that hold us together, and islands that keep us apart. Some islands, special for spiritual reasons, are to be visited only by the elect; others are strictly reserved for prisoners. Some, with material resources, have been occupied by a few families for centuries, while other islands, with no resources at all, are now home to thousands of residents.

People have gone to war over islands, as they did with the Falklands and the island of Run (now part of Indonesia), which was the only source of the precious spice nutmeg during the seventeenth century. And islands have been instrumental in making peace: the British ceded the very same Run to the Dutch in 1667 in exchange for Manhattan, and France traded its part of Canada (and more) to Britain in 1763 in order to secure Guadeloupe and Martinique--because of the islands'' sugar cane. Many islands stay put, like sentinels of the sea and guardians of the straight and narrow, and others move about with the wind or the current or the quirks of fate, like the Flemish sandbanks and Sable Island (off the coast of Nova Scotia) and the floating islands of roots and vegetation in the Florida Everglades and in the Tigris-Euphrates Delta. Some islands disappear and reappear--the Halligen islands in the North Sea during stormy season, Falcon Island in the Pacific once in a volcanic blue moon--while others can be reached on foot, but only at low tide. And there have been man-made islands for thousands of years, from the crannogs in ancient Ireland and Scotland to the prehistoric villages built on stilts in Alpine lakes. There are islands we escape to--and islands we escape from. Some of them are real, and some are imagined. When mapmaking became a cultural tradition--especially in Europe and Asia--as well as a travel guide, plenty of imaginary islands appeared on these "real" maps.

Commerce played a big role in this. No one ever landed on the mythical island of Buss in the North Atlantic, for example, but it was still charted on maps and even chartered to the Hudson''s Bay Company to harvest furs. Such islands are both there and not there--like stories. "It was, and it was not" is the phrase used by storytellers on the island of Majorca when they begin. Maybe stories themselves began with islands, for islands have fascinated people as long as they have been singing songs and telling tales and traveling, and have found counterparts in the islands that are our homes and gardens and towns and farms, as well as our personalities. For millennia, seafarers and settlers and storytellers have sought out islands for reasons that go deep into the human psyche and haunt its imagination, even--or sometimes especially--when ignorant of geography. It may have something to do with the way an island rises up from the sea and then sooner or later disappears again, perhaps invoking a primordial consciousness of the beginning and the end of life. Or it may be connected to the journey between the mainland and an island, and between one island and another, requiring the crossing of water.

This has haunted humans since time immemorial; the word "metaphor," the signature of stories and songs, means "to carry across." Islands have provided a special invitation to fertile imaginations, just as they did (in evolutionary theory) to unique mutations. There have been countless islands where marvelous--or malicious--things supposedly happened, and memorable islands that came into being as fiction took up history, with stories of true island adventures (survivor stories long before reality TV) sponsoring novels like Robinson Crusoe. Psychiatry began with an awareness of "islanded" psyches, and anthropology made islands an academic fetish (and a travel excuse), with island accounts beginning in the late nineteenth century by Arthur Haddon on the Torres Strait Islands and Alfred Radcliffe-Brown on the Andamans, and then by Bronislaw Malinowski on the Trobriand Islands and Margaret Mead on Samoa. Islands represent both paradise and purgatory, just as they invoke madness and invite magic. They have been places where curious things occur--or where nothing at all takes place. But even then, the howling noises of the sea or the deep silence of a lake will often conjure up a sense of strangeness around islands, and generate stories about the unusual things that go on there. Many poets, from the Scandinavian skald to the Swahili sha''ir and from Homer (in the Odyssey) to Shakespeare (in The Tempest), have located some of their most intriguing stories on islands.

Later, Jonathan Swift took readers to islands of wonderment on Gulliver''s travels, Alexandre Dumas to the treasure of Monte Cristo, and H. G. Wells to the menacing Island of Dr. Moreau. And they are certainly places where fabled creatures live: there are real islands with dragons, like Komodo in Indonesia, and imaginary islands with dragons, like those in the Chronicles of Narnia. There are islands of solitude, and islands with a social life--though not always an easy one. So is the ultimate appeal of islands "home"--or "away"? Ideals of civilized life, domestic and settled, are routinely represented in island images, but so are concepts of the wild and the barbaric; and both of them may sustain the sense of community that islands often celebrate. The history of islands is also the history of our planet, from its beginning as an island in space to its current position as part of the archipelago that is our solar system, and from the moment land first appeared above the waters that covered the earth to the contemporary appearance and disappearance of islands in the cycles of climate change and seismic upheaval that make up and break up our world.

All of which raises--or complicates--the question: What is an island? Is it simply land surrounded by water, which the etymology of the word in various languages suggests? Do tidal islands, and isolated peninsulas, qualify? How about man-made islands, like oil rigs or waterfront real estate developments--or castles surrounded by moats? Is size a factor, with small being beautiful? But then, what is it that a reef or a rock outcrop have in common with Greenland or New Guinea? And what about continents like Australia and Antarctica? Do geology and geography set the standard for island identity, or politics and economics? Are islands defined by their natural history--or by their human history? One thing is certain: barren or beautiful, large or small, real or imagined, islands are a central part of the world we live in. They represent much of what we dread, and much of what we desire. And since so many of our thoughts and feelings have an island counterpart, they may well define what it is to be human.