The subtitle of [Broca's Brain], "Reflections on the Romance of Science," encapsulates its blend of accepted fact with personal conjecture. In Sagan's world the romance is not monogamous; it is a flirtation with virtually every branch of thought and study. Science qua science lies at its heart, but other relationships provide zest and perspective. In the introduction, Sagan warns that, as is his wont, he has not hesitated to interject social, political, or historical remarks. If he had, this might become his last popular book. His core topics—planetary exploration, the quest for extraterrestrial intelligence, cosmic evolution—are intrinsically fascinating, but other writers address them too. Sagan's secret lies not just in subject but in insight and perspicacious linkages.

In these Broca's Brain abounds, but in flow it wants badly. Its five large parts and 25 chapters connect only loosely—hardly surprising given their heterogeneous origins, many having been derived or reprinted from earlier work. Nor is the volume lavishly produced—stunning color plates can be found elsewhere; ideas dominate here.

Sagan gives us a devastating debunking of several pseudoscientific theories, a fairly technical history of American astronomy, a pithy yet synoptic commentary on cosmology, a balanced encomium to science and technology, a personal critique of science fiction. But it all begins with Paul Broca, a major 19th-century neurologist and anthropologist, who founded modern brain surgery. Today, in Paris, a hundred years after his death, his bizarre Musée de l'Homme survives, with its collections of skeletons and skulls, shrunken heads and bottled fetuses, and scores of human brains—including his own. Recounting a visit to the museum, when he held the cylindrical bottle containing Broca's brain, Sagan launches chapter 1 with a jolting free association, teaching historical anthropology and brain physiology while speculating: In some sense, is "Paul Broca still there in his formalin-filled bottle?… Might it be possible at some future time, when neurophysiology has advanced substantially, to reconstruct the memories or insights of someone long dead?"

And so it goes. From expression of wonderment over nature's duality of complexity and knowableness to a succinct biography of [Albert] Einstein, from an exposition of comparative planetary climatology to a comparison of science and theology, from contemplation of the origin of the Kaaba to musings over the end of the universe, the prose rushes forward. Topics outside Sagan's fields of formal education generally are treated philosophically or speculatively; in his areas of expertise, however, details abound.

Here, as in much of his earlier writing, Sagan ridicules chauvinism, broadly conceived; thus, solar system nomenclature should be "deprovincialized" to include recognition of other cultures and persons other than scientists, and even the use of robots to perform human functions is defensible. Sagan sees objections to the latter as a form of "speciesism," the "prejudice that there are no beings so fine, so capable, so reliable as human beings." Still, he himself cannot accept life centering on elements other than carbon, surviving in habitats other than planets, or evolving technologically in ways radically different from our own. Even though he has considered such possibilities more than anyone else, the world as we understand it simply does not seem to him to admit certain alternatives.

More than in his past books, Sagan here contemplates pseudoscience and religion. His trenchant, somewhat technical rebuttal to [Immanuel] Velikovksy reappears here, along with an unnecessarily detailed criticism of a modern numerologist who claims to be God. Sagan's analysis of UFO's and ancient astronaut theories will not convince true believers; but for all others his evidence should be compelling.

At first his attack on pseudoscience occupying more than a fourth of the book, seems like overkill. But this lengthy section squarely addresses seemingly mysterious topics and illogical reasoning patterns that commonly bewilder and befuddle the public. As modern astronomy, for example, has brought forth mind-boggling concepts, the esoteric yet plausible ironically has sounded increasingly like the fantastic and pseudoscientific, particularly to nonspecialists. Surely scientists have an obligation to the public that supports them to explain the differences and to share what they know of science's beauty, but too few do so. For this reason Sagan's thoughtful and articulate analysis is particularly valuable.

In contrast, Sagan's discussion of science and theology seems unsettlingly dilettantish: Either he has cut incisively through centuries of thought and reflection or he does not fully understand the issues. Many of us would agree with his piquant views, but, laconic rather than compendious in his analysis, he has trivialized a complex subject. He proceeds with tact and caution unusual for him, although it is unlikely that much of what he says will shock either scientist or theologian, especially in our post-God-is-dead era. (pp. 38-9)

Drollery distinguishes the memorable from the routine, and Broca's Brain contains the usual array of Saganisms. A sample:

• At an International Astronomical Union meeting, Moscow was officially ruled to be a state of mind.

• According to Jacob Bronowski, all the Easter Island monoliths resemble Benito Mussolini.

• "Both [P. T.] Barnum and H. L. Mencken are said to have made the depressing observation that no one ever lost money by underestimating the intelligence of the American public."

• Re pseudoscientists, "The fact that some geniuses were laughed at does not imply that all who are laughed at are geniuses. They laughed at Columbus, they laughed at [Robert] Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown."

To the specialist, much of the information Sagan puts forth in the book will be familiar or seem conjectural. But even for such a reader there will be fresh insights. Sagan's ruminations raise a torrent of disturbing questions…. Sagan suggests connections—some possibly invalid—that others have not even surmised. That is one of the virtues of the book. Responsible, creative scientists occasionally should wonder aloud, even about their discipline's social dimensions, connections with other enterprises, and future prospects.

For the nonspecialist, the book will be frustrating reading, with uneven technical detail, loose connections, and an overabundance of polysyllabic jargon. But if the reader can make it through, this curious volume can answer old questions, raise new ones, open vistas, become unforgettable.

In short, Sagan has done it again. The book's title may be Broca's brain, but its subject is Sagan's. (pp. 39-40)