On the 10th anniversary of his death, brilliant astrophysisist and Pulitzer Prize winner Carl Sagan's prescient exploration of the relationship between religion and science and his personal search for God.

Carl Sagan is considered one of the greatest scientific minds of our time. His remarkable ability to explain science in terms easily understandable to the layman in bestselling books such as Cosmos, The Dragons of Eden, and The Demon-Haunted World won him a Pulitzer Prize and placed him firmly next to Isaac Asimov, Stephen Jay Gould, and Oliver Sachs as one of the most important and enduring communicators of science. In December 2006 it will be the tenth anniversary of Sagan's death, and Ann Druyan, his widow and longtime collaborator, will mark the occasion by releasing Sagan's famous "Gifford Lectures in Natural Theology," The Varieties of Scientific Experience: A Personal View of the Search for God.

The chance to give the Gifford Lectures is an honor reserved for the most distinguished scientists and philosophers of our civilization. In 1985, on the grand occasion of the centennial of the lectureship, Carl Sagan was invited to give them. He took the opportunity to set down in detail his thoughts on the relationship between religion and science as well as to describe his own personal search to understand the nature of the sacred in the vastness of the cosmos.

The Varieties of Scientific Experience, edited, updated and with an introduction by Ann Druyan, is a bit like eavesdropping on a delightfully intimate conversation with the late great astronomer and astrophysicist. In his charmingly down-to-earth voice, Sagan easily discusses his views on topics ranging from manic depression and the possibly chemical nature of transcendance to creationism and so-called intelligent design to the likelihood of intelligent life on other planets to the likelihood of nuclear annihilation of our own to a new concept of science as "informed worship." Exhibiting a breadth of intellect nothing short of astounding, he illuminates his explanations with examples from cosmology, physics, philosophy, literature, psychology, cultural anthropology, mythology, theology, and more. Sagan's humorous, wise, and at times stunningly prophetic observations on some of the greatest mysteries of the cosmos have the invigorating effect of stimulating the intellect, exciting the imagination, and reawakening us to the grandeur of life in the cosmos.

"In 1877, the Italian astronomer Giovanni Schiaparelli was looking at Mars through his new telescope, and he noticed intricate etchings in the equatorial region of the planet's surface. Schiaparelli called these lines canali, by which he probably meant something like 'gullies' or 'grooves,' but his coinage got wrongly translated into English as 'canals.' It was a regrettable linguistic slip.

... Washington Post Book Review (read the entire Washington Post review) The idea of Martian canals grabbed the imagination of American astronomer Percival Lowell, scion of the famous Boston Lowell clan, who spun out an elaborate story of a Martian civilization with a central planetary government and the technological wizardry to engineer a massive system of aqueducts. Lowell even used his own Arizona observatory to identify the Martian capital, called Solis Lacus.

There are no canals on Mars. No cities either, and no government. Indeed, no signs of past life whatsoever, as we know today. All of this was an elaborate phantasm of Lowell's fertile mind, yet as late as the 1950s, popular culture was saturated with imagery of Martians as a technologically advanced extraterrestrial race.

The late Carl Sagan used the misbegotten tale of Martian engineers, in his 1985 Gifford Lectures in Natural Theology at the University of Glasgow, as a cautionary tale about the power of belief and yearning to trump science and reason. The Cornell University astrophysicist, Pulitzer Prize-winning author and TV personality was alarmed by the persistence of such magical thinking even into the late 20th century, despite tremendous scientific progress in understanding both human nature and the cosmos. He used the prestigious lecture series (collected here for the first time by his widow and longtime collaborator, Ann Druyan) as an opportunity to challenge the evidence for everything from the Bermuda Triangle to UFOs to angels and deities. But just as important, he used the lectures to spell out his views on the common ground shared by science and spirituality.

Sagan does not deny the existence of God. Nor does he affirm it. As he quips in the lively Q&A section appended to the lectures, 'Absence of evidence is not evidence of absence.' What Sagan does do is insist on the primacy of scientific method and scientific evidence, and he holds the many and various 'proofs' of God's existence up to these scientific standards. Most are found wanting. But Sagan is not harsh in his critiques of religious thought; he is more perplexed by theology's narrow and unimaginative vision.

Why would an all-powerful God work only on a local (and recent) project like the Earth when there is a vast, 15-billion-year-old universe out there, with countless galaxies containing countless stars and the possibility of countless worlds? Why didn't God let us know about quantum mechanics and natural selection and cosmology from the get-go? And why would theologians insist on such a provincial version of the creation and God's imagination?

Sagan is not being flip or heretical, though he is intellectually playful and obviously likes the fray. Sagan took his own spirituality seriously — indeed, he defined science as 'informed worship.' The closest he comes to articulating his own view of God is to describe admiringly the philosophies of Spinoza and Einstein, who basically considered God the sum total of all the laws of physics. These laws, he emphasizes again and again, govern not just the Earth and humanity but every solar system and every star and every galaxy. They are not local ordinances.

Central to Sagan's personal search for the existence of God is the question of other life in the universe. For him, the requirements for proof of extraterrestrial intelligence are essentially the same requirements for proof of angels or demigods or a God. Sagan spends much of one lecture on the so-called Drake equation, which is a way of estimating the number of technologically advanced civilizations in the galaxy. The equation incorporates several values, including the rate of star formation, the fraction of stars with planets around them, the fraction likely to have evolved intelligent life and so forth.

The confounding value is L, which stands for the average lifetime of a technologically advanced civilization. If you plug in an optimistic value, assuming such civilizations are long-lived, then the equation predicts that there are millions of intelligent societies out there, and likely one just a few hundred light years away. That's a long way by spaceship, but really right next door if you're going at the speed of light, which means that our radio telescopes should be able to pick up signals from other advanced beings who want to contact us.

But what if the value of L is low? What if technologically advanced civilizations don't last very long on average? If highly intelligent races tend to perish quickly, then the Drake equation predicts not millions of such civilizations but one. Us. We are alone.

In 1985, Sagan was especially concerned about the 55,000 nuclear warheads strategically placed around the globe, threatening to make Earth a cosmological loser. A recurring theme in these lectures is that our scientific prowess is double-edged, revealing the awesomeness of nature while landing us in great peril.

Yet this is not a dour book. Far from it. Sagan was fundamentally an optimist, and 'The Varieties of Scientific Experience' is mostly a joyful, celebratory meditation on nature and the expansiveness of the human spirit. The volume was published on the 10th anniversary of Sagan's death in December 1996. For those who have sorely missed his clear and wise voice, it will be received as a gift.

Wray Herbert writes the 'Mind Matters' column for Newsweek.com.

" Reviewed by Wray Herbert, Washington Post Book World (Copyright 2006 Washington Post Book World Service/Washington Post Writers Group)
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"Find here a major fraction of this stunningly valuable legacy left to all of us by a great human being. I miss him so." Kurt Vonnegut

In his charmingly down-to-earth voice, the late astronomer Carl Sagan discusses the relationship between religion and science and describes his own personal search to understand the nature of the sacred in the vastness of the cosmos.

Carl Sagan was Professor of Astronomy and Space Sciences and Director of the Laboratory for Planetary Studies at Cornell University. He played a leading role in the Mariner, Viking, and Voyager spacecraft expeditions to the planets, for which he received the NASA medals for Exceptional Scientific Achievement. Dr. Sagan received the Pulitzer Prize and the highest awards of both the National Academy of Sciences and the National Science Foundation, and many other awards, for his contributions to science, literature, education, and the preservation of the environment. His book Cosmos (accompanying his Emmy- and Peabody Award-winning television series of the same name) was the bestselling science book ever published in the English language, and his bestselling novel, Contact, was turned into a major motion picture.