The voyage was brutal for Felipa. She had never been seasick before, and by the time they arrived at Porto Santo, Dona Moniz was sure that she and Columbus had already conceived a child. Sure enough, nine months later Diego was born. Felipa took a long time recovering from the pregnancy and birth, but as soon as she was strong enough she devoted herself to the child. Her mother viewed this with some distaste, since there were nurses for that kind of thing, but she could hardly complain, for it soon became obvious that Diego was all that Felipa had; her husband did not seem hungry for her company. Indeed, he seemed eager to get off the island at every opportunity -- but not for the sake of getting to court. Instead, he kept begging for chances to get onto a ship sailing along the African coast.

The more he begged, the less likely it seemed that he would get a chance to join a voyage. He was, after all, Genovese, and it occurred to more than one ship's captain that Columbus might have married into a sailing family as a ploy to learn the African coast and then return to Genova and bring Italian ships into competition with the Portuguese. That would be intolerable, of course. So there was never a question of Columbus getting what he really wanted.

With her husband so frustrated, Felipa began to pressure her mother to do something for her Cristovao. He loves the sea, Felipa said. He dreams of great voyages. Can't you do something for him?

So she brought her son-in-law into her late husband's library and opened for him the boxes of charts and maps, the cases of precious books. Columbus's gratitude was palpable. For the first time it occurred to her that perhaps he was sincere -- that he had little interest in the African coast, that it was navigation that inspired him, voyaging for its own sake that he longed for.

Columbus began to spend almost every waking moment poring over the books and charts. Of course there were no charts for the western ocean, for no one who had sailed beyond the Azores or the Canaries or the Cape Verde Islands ever returned. Columbus learned, though, that the Portuguese voyagers had disdained to hug the coast of Africa. Instead, they sailed far out to sea, using better winds and deeper waters until their instruments told them that they had sailed as far south as the last voyage had reached. Then they would sail landward, eastward, hoping that this time they were farther south than the southernmost tip of Africa, that they would find a route leading eastward to India. It was that deep-sea sailing that had first brought Portuguese sailors to Madeira and then to the Cape Verde Islands. Some adventurers of the time had imagined that there might be chains of islands stretching farther to the west, and had sailed to see, but such voyages always ended in either disappointment or tragedy, and no one believed anymore that there were more islands to the west or south.

But Columbus could not disregard the records of old rumors that once had led sailors to search for westward islands. He devoured the rumors of a dead sailor washed ashore in the Azores or Canaries or Cape Verdes, a waterlogged chart tucked into his clothing showing western islands reached before his ship sank, the stories of floating logs from unknown species of tree, of flocks of land birds far away to the south or west, of corpses of drowned men with rounder faces than any seen in Europe, dark and yet not as black of skin as Africans, either. These all dated from an earlier time, and Columbus knew they represented the wishful thinking of a brief era. But he knew what none of them could know -- that God intended Columbus to reach the great kingdoms of the east by sailing west, which meant that perhaps these rumors were not all wishful thinking, that perhaps they were true.

Even if they were, however, they would be unconvincing to those who would decide whether to fund a westward expedition. To persuade the king would mean ftrst persuading the learned men of his court, and that would require serious evidence, not sailors' lore. For that purpose the real treasure of Porto Santo were the books, for Perestrello had loved the study of geography, and he had Latin translations of Ptolemy.

Ptolemy was cold comfort for Columbus -- he had it that from the westernmost tip of Europe to the easternmost tip of Asia was 180 degrees, half the circumference of the earth. Such a voyage over open ocean would be hopeless. No ship could carry enough supplies or keep them fresh long enough to cover even a quarter of that distance.

Yet God had told him that he could reach the Orient by sailing west. Therefore Ptolemy must be wrong, and not just slightly wrong, either. He must be drastically, hopelessly wrong. And Columbus had to find a way to prove it, so that a king would allow him to lead ships to the west to fulfill the will of God.

It would be simpler, he said in his silent prayers to the Holy Trinity, if you sent an angel to tell the King of Portugal. Why did you choose me? No one will listen to me.

But God didn't answer him, and so Columbus continued to think and study and try to figure out how to prove what he knew must be true and yet no one had ever guessed -- that the world was much, much smaller, the west and east much closer together than any of the ancients had ever believed. And since the only authorities that the scholars would accept were the books written by the ancients, Columbus would have to ftnd, somewhere, ancient writers who had discovered what Columbus knew had to be the truth about the world's size. He found some useful ideas in Cardinal d'Ailly's Imago Mundi, a compendium of the works of ancient writers, where he learned that Marinus of Tyre had estimated that the great landmass of the world was not 180 degrees, but 225, leaving the ocean to take up only 135 degrees. That was still much too far, but it was promising. Never mind that Ptolemy lived and wrote after Marinus of Tyre, that he had examined Marinus's figures and refuted them. Marinus offered a picture of the world that helped build Columbus's case for sailing west, and so Marinus was the better authority. There were also helpful references from Aristotle, Seneca, and Pliny.

Then he realized that these ancient writers had been unaware of Marco Polo's discoveries on his journey to Cathay. Add 28 degrees of land for his findings, and then add another 30 degrees to account for the distance between Cathay and the island nation of Cipangu, and there were only 77 degrees of ocean left to cross. Then subtract another 9 degrees by starting his own voyage in the Canaries, the southwestern islands that seemed the likeliest jumpingoff point for the sort of voyage God had commanded, and now Columbus's fleet would only have to cross 68 degrees of ocean.

It was still too far. But surely there were errors in Marco Polo's account, in the calculations of the ancients. Take off another 8 degrees, round it down to a mere 60! Yet it was still impossibly far. One-sixth of the Earth's circumference between the Canaries and Cipangu, and yet that still meant a voyage of more than 3,000 miles without a port of call. Bend or twist them as he might, Columbus couldn't make the writings of the ancients support what he knew to be true: that it was a matter of days or at most weeks to sail from Europe to the great kingdoms of the east. There had to be more information. Another writer, perhaps. Or some fact that he had overlooked. Something that would persuade the scholars of Lisbon to respect his request and recommend to King Jodo that he give Columbus command of an expedition.

Through all of this, Felipa was obviously baffled and frustrated. Columbus was vaguely aware that she wanted more of his time and thought, but he couldn't concentrate on the silly things that interested her, not when God had set such a Herculean labor for him to accomplish. He hadn't married her to play at housekeeping, and he said so. He had great works to accomplish. But he couldn't explain what that great work was, or who had given it to him to accomplish, because he had been forbidden to tell. So he watched Felipa grow more and more hurt even as he grew more and more impatient with her obvious hunger for his company.