GREGG EASTERBROOK reviews for the New York Times a new book, 'Collapse': How the World Ends by Jared Diamond, author of the best reader, Guns, Germs and Steel.

EIGHT years ago Jared Diamond realized what is, for authors, increasingly a fantasy -- he published a serious, challenging and complex book that became a huge commercial success. ''Guns, Germs, and Steel'' won a Pulitzer Prize, then sold a million copies, astonishing for a 480-page volume of archeological speculation on how the world reached its present ordering of nations. Now he has written a sequel, ''Collapse,'' which asks whether present nations can last. Taken together, ''Guns, Germs, and Steel'' and ''Collapse'' represent one of the most significant projects embarked upon by any intellectual of our generation. They are magnificent books: extraordinary in erudition and originality, compelling in their ability to relate the digitized pandemonium of the present to the hushed agrarian sunrises of the far past. I read both thinking what literature might be like if every author knew so much, wrote so clearly and formed arguments with such care. All of which makes the two books exasperating, because both come to conclusions that are probably wrong.

 ''Guns'' asked why the West is atop the food chain of nations. Its conclusion, that Western success was a coincidence driven by good luck, has proven extremely influential in academia, as the view is quintessentially postmodern. Now ''Collapse'' posits that the Western way of life is flirting with the sudden ruin that caused past societies like the Anasazi and the Mayans to vanish. Because this view, too, is exactly what postmodernism longs to hear, ''Collapse'' may prove influential as well.

 Born in Boston in 1937, Diamond is a professor of geography at the University of California, Los Angeles. Initially he specialized in conservation biology, studying bird diversity in New Guinea; in 1985 he won one of the early MacArthur ''genius grants.'' Gradually he began to wonder why societies of the western Pacific islands never developed the metallurgy, farming techniques or industrial production of Eurasia. Diamond also studied the application of natural-selection theory to physiology, and in 1999 received a National Medal of Science for that work, which is partly reflected in his book ''Why Is Sex Fun?'' (Sex is fun; the book is serious.) Today Diamond often returns to the Pacific rim, especially Australia, where in the outback one may still hear the rustle of distant animal cries just as our forebears heard them in the far past.

 ''Collapse'' may be read alone, but begins where ''Guns, Germs, and Steel'' ended: essentially the two form a single 1,000-page book. The thesis of the first part is that environmental coincidences are the principal factor in human history. Diamond contends it was chance, not culture or brainpower, that brought industrial power first to Europe; Western civilization has nothing to boast about.

 Many arguments in ''Guns'' were dazzling. Diamond showed, for example, that as the last ice age ended, by chance Eurasia held many plants that could be bred for controlled farming. The Americas had few edible plants suitable for cross-breeding, while Africa had poor soil owing to the millions of years since it had been glaciated. Thus large-scale food production began first in the Fertile Crescent, China and Europe. Population in those places rose, and that meant lots of people living close together, which accelerated invention; in other locations the low-population hunter-gatherer lifestyle of antiquity remained in place. ''Guns'' contends the fundamental reason Europe of the middle period could send sailing ships to explore the Americas and Africa, rather than these areas sending sailing ships to explore Europe, is that ancient happenstance involving plants gave Europe a food edge that translated into a head start on technology. Then, the moment European societies forged steel and fashioned guns, they acquired a runaway advantage no hunter-gatherer society could possibly counter.