The eternal silence of these infinite spaces terrifies me," Blaise Pascal noted in his Pensées, that extraordinary jumble of philosophical jottings that the seventeenth-century French philosopher set down toward the close of his life. The startling phrase leaps up suddenly at the reader just a few lines below the equally famous passage in which Pascal declares, "A human being is only a reed, the weakest in nature, but he is a thinking reed. To crush him, the whole universe does not have to arm itself. A mist, a drop of water, is enough to kill him. But if the universe were to crush the reed, the man would be nobler than his killer, since he knows that he is dying, and that the universe has the advantage over him. The universe knows nothing about him." And then, a sudden, jarring leap to the next level of response, as powerful as it is unexpected, that stunning line:

The eternal silence of these infinite spaces terrifies me.

I’ve been thinking about those infinite spaces, and their terrifying eternal silences, quite a bit since the death last year of Poul Anderson. Poul was the poet of the spaceways. More than anyone else in modern science fiction, he made us feel the immensity of space, the darkness of it, the silence, and, yes, the terror of which Pascal spoke three and a half centuries ago. From such early works as The Snows of Ganymede and No World of Their Own on through Tau Zero and "Call Me Joe" to the most recent of his innumerable novels and stories, he showed us the strangeness and awesomeness of the universe in a way that was at once exhilarating and sobering.

Even our best writers are guilty of making the cosmos seem an excessively cozy place. Consider Isaac Asimov’s famous Foundation series, in which the inhabitants of the twenty-five million inhabited worlds of the Galactic Empire zip merrily about from planet to planet, going from Trantor to Siwenna to Terminus ever so much more easily than a citizen of Rome could have gone from Naples to Alexandria. The Foundation novels are charming and delightful books, and science fiction readers will cherish them to the end of time, but their great flaw is that they reduce interstellar travel to the level of a trip on the New York subway system. (Isaac didn’t like to fly, and rarely went very far from New York City.) Frank Herbert’s Dune books, though set in a very different sort of stellar empire, nevertheless have the same inescapable flaw. All galactic-empire stories do. They are inherently reductive in nature. They turn whole clusters of stars into downscaled metaphors that make them seem to be nothing more than aggregations of counties and towns, and they make the gigantic dark emptinesses between the galaxies seem like the grassy patches of scruffy wasteland that separate the suburbs of one medium-sized city from the suburbs of the next.

One great character of literature who never let humility stand in his way, and yet who surely stared outward into the unfathomable universe with the same mixture of awe and hungry fascination that Poul Anderson showed us so often, was Odysseus, King of Ithaca. He was the prototypical explorer, burning with the need to look upon the mysteries that lie beyond the horizon.

Homer’s immortal epic poem traces Odysseus’s ten-year-long journey homeward from the Trojan War, taking him from island to island around the Mediterranean in a way that demonstrates that the insatiably curious Odysseus was not in as much of a hurry to get home as many of us, under the same circumstances, would have been. He wanted to see and experience everything that lay in his path, and did. (SF writers have been rewriting The Odyssey ever since. Fletcher Pratt did it fifty years ago in a fine novella called "The Wanderer’s Return"; Philip José Farmer’s The Green Odyssey appeared a few years later; and more recently we have had, among many others, the Star Trek: Voyager series.)

Odysseus made one last voyage after his return from Troy. Homer doesn’t tell us about it, but Dante does, in the twenty-sixth canto of The Inferno, and it’s a wonderful story, which I’m sure Poul Anderson must have known. It shows Odysseus ("Ulysses," Dante calls him, using the Latin form) as a perfect Andersonian voyager, awed but in no way cowed by the unattainability of the unconquered worlds that lie before him.

It is a story that Dante apparently invented, since there seems to be no Greek or Roman antecedent for it. Dante, recounting his journey through Hell, is deep in the Eighth Circle now, among the "Fraudulent Counselors," those who had injured others through trickery. Cunning Odysseus has been sent to Hell for devising the Trojan horse, by which Troy finally was conquered. To Dante the shade of Odysseus tells a tale, not the familiar one of his journey home to Ithaca, but of what happened afterward, when, driven by "the restless itch to rove," he felt impelled to leave his beloved wife and his aged father and his son and set forth once more, "on the deep and open sea, with a single ship and that little band of comrades who even then had not deserted me."

Off they go on a final Odyssey, westward into the Mediterranean, with Africa on their left and the coast of Spain on their right, until they find themselves staring at the open sea, the uncharted Atlantic. "Brothers," Odysseus says, "you who have passed through a hundred thousand perils to reach this place, do not deny yourself this last exploit. Here lies a chance to learn for yourself what lies in this unknown world on the far side of the sun, where no people dwell." He tells his men that they had not been born to live in brutish ignorance, but for the pursuit of knowledge and excellence: and so they put their shoulders to their oars and eagerly go forward into the unplumbed ocean that stands before them.

The path Odysseus takes goes toward the southwest. On and on they go, presumably toward the place we now know as Brazil. Soon they pass the Equator; the familiar northern stars slip below the horizon, and they sail beneath the unfamiliar constellations of the other hemisphere. At last a mountain looms before them in the sea, "dark in the distance," says Odysseus, "and so lofty and so steep, I had never seen its like before." It is, Dante will explain to us much later in his great poem, the mountain of Purgatory; but Odysseus has no knowledge of that. He and his crew rejoice at the sight of land, and head vigorously toward it. But then a fierce storm comes toward them out of the newly discovered shore, and the voyagers’ ship is caught by whirlwinds and spun three times around. The fourth spin is the fatal one: the stern rises, the prow sinks, and the sea closes over Odysseus and his men, for Odysseus must not reach Purgatory, but is destined to burn forever among his fellow tricksters in Hell’s Eighth Circle.

The failure of Odysseus’s final voyage is not important. What matters is that he made it: that he stood by the Pillars of Hercules, looking westward into the great ocean that no one before him had dared to enter, and, putting aside all terror and awe, urged his companions forward for the sake of the pursuit of knowledge and excellence.

A great dark ocean lies all about our world. Blaise Pascal looked up into it and shivered with primordial terror. I looked up into it once and aimed my flashlight at the inhabitants of the stars. Again and again Poul Anderson reminded us that venturing into that black void would be something quite different from taking the 9:15 train from Penn Station to Connecticut, something frightening and humbling, but that some of us–some–would attempt that voyage even so. m