Koestler's monument to himself; Bricks to Babel, by Arthur Koestler. New York: Random House. $20.

Arthur Koestler is one of those intellectuals -- more numerous in Europe than in America -- whose lives fall into two acts. Most people probably know the Koestler of Act 1: the political writer and author of "Darkness at Noon," a novel about the wiles and perils of communism, an ideology Koestler idealistically embraced and then angrily renounced. Other people know best the Koestler of Act 2: the student of science and theorist of creativity.

Although both acts glow with intellectual energy and polemical fervor, they seem but little connected. And Koestler is the first to concede that his life was split by a "vocational change." In its first half, he says, that life was "a typical case history of a Central European member of the educated middle class born in the first years of our century." The second half of his life has not been so typical. Koestler abandoned politics for the tranquil occupations of science and philosophy. Yet his two lives are more closely connected than they first appear. To disclose the bonds between them, Koestler has gathered together this "omnibus" of excerpts from his writings of 50 years.

This volume shows that however disparate his pursuits, Koestler has been animated since youth by a single desire: to hold unequivocal truth in his hands. This desire has driven him from intellectual adventure to misadventure -- from early studies in science to Zionism and then to communism; from anti-Nazism to the Spanish Civil War and then to anti-Stalinism; from cold war partisanship back to science and philosophy and on into meditations on "cosmic consciousness."

The hunger for certainly makes Koestler a questionable guide through the rough terrain of the 20th century since he brooks no caution and shuns ambiguity. But it also gives him an eye for errors and possibilities overlooked by less demanding observers. Hence he spots contradictions in many Utopian ideals, not only in Zionism and communism but in of Gandhism and Zen. He finds coherence and hope where others do not -- in art, science, nature, and human life.

The quest for metaphysical unity and certainty has been Koestler's chief occupation for the past 25 years. It has yielded a notable series of books advancing the idea that creativity in all subjects is rooted in one experience: the fashioning of new wholes out of previously disorganized parts. The quest has resulted in a complementary theory of nature and organic activity. Inventing a new vocabulary, Koestler maintains that all nature and life activity are arranged in a hierarchy, or "holarchy," composed of "holons." Each of these basic elements is a whole in relation to those below it in the holarchy but only a part in relation to those about. Thus all things can be viewed as "holons" possessing the powers of integration and transcendence and pointing toward --what else but -- cosmic consciousness. At 75, Koestler has lost none of his schoolboy yearnings for the absolute.

One cannot wade through these 700 pages without wondering whether Koestler's ideas, mostly culled in long extracts from books (including novels and autobiographies) and held together by bits of commentary, warrant quite the reverence bestowed upon them in this form. Had the book been compiled by an adroit editor rather than by the author we would have had a solid piece of intellectual history. Instead we have an intellectual self-celebration.

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