Cienfuegos is a city laid out by people who believed in straight lines. It was founded in 1819 by French families, some from Bordeaux and some by way of Louisiana, and they drew the streets on paper before they cut a single tree, every street meeting every other at a right angle, the blocks as square as a chessboard. I did not know as a boy that this was unusual. I thought all cities were made that way, and that the crooked streets of Havana, when I finally saw them, were a mistake someone ought to correct. It may be that I became a mathematician because I was born on a piece of graph paper.

The other thing about Cienfuegos is the bay. The Bahía de Jagua is large and nearly closed, with a narrow mouth to the Caribbean Sea that is guarded by an old Spanish fort, the Castillo de Jagua, on its hill. Inside the mouth the water is calm and green, and the city sits on it the way a cat sits on a windowsill, looking out. We called Cienfuegos la Perla del Sur, the Pearl of the South. Every city in Cuba has a name like that for itself. Ours happened to be true.

I was born on a Sunday in March of 1925, in a narrow house four blocks from the water. My father, Manuel Rodas, was a bookkeeper for a company that kept sugar warehouses at the port. My mother, Eva Reynosa, sewed for the ladies of the neighborhood at a machine by the front window, where the light was good. I was their only child to live past infancy. I understood this only later, from the way my mother watched me cross a street.

The port is my first memory. My father would take me on Saturday mornings to the warehouses, where he had to check figures, and I would sit on a sack in the shade of the great doors and watch the ships. In the harvest months the sugar came down from the mills on the railroad and went into the holds of ships from England and the United States and Holland, and the whole waterfront smelled of it, sweet and burnt, a smell that got into your clothes and your hair. Men carried the sacks on their shoulders up narrow planks into the ships, one after another, all day, singing sometimes to keep the rhythm. My father checked the count against the bills of lading in his beautiful handwriting. He could add a column of four-figure numbers faster than I could read it, without moving his lips, and he never made an error. I thought he was the most intelligent man alive. I still think he may have been among them.

He was not an educated man in the formal sense. His own father had taken him out of school at twelve to work. Perhaps that is why books were his one extravagance. My mother would say, not unkindly, that some men drink and some men gamble and her husband buys paper.

There was a bookseller on a street near the Parque Martí, the main square, whose name I have sadly forgotten, an old Asturian with a white mustache who kept his shop dark to protect the bindings. On the last Saturday of each month, after my father was paid, we went there together. I was allowed one book. My father was allowed one book, but more often than not he spent his turn on me as well.

The first books I owned were volumes of El Tesoro de la Juventud, the Treasury of Youth, which was a great encyclopedia for children in twenty volumes, sold all over Latin America in those years. We could not afford the set. We bought it one used volume at a time, out of order, as they came into the shop, so that I learned about the Egyptians long before the Greeks and knew the life of the honeybee years before I could have told you how a ship floats. It did not matter. Each volume had stories and poems and things to make, and in each one a section of games and pastimes, with puzzles and little problems of arithmetic. I did the puzzles first. Then I read the rest.

When I was ten, my father brought home La isla misteriosa, by Julio Verne, which is The Mysterious Island in English. It is the story of five men who escape from a war in a balloon and are thrown down on an island in the Pacific with nothing at all, not a knife, not a match. The hero is an engineer, and he rebuilds civilization on that island from the ground up by knowing things. He makes fire, bricks, iron, glass, a telegraph. At one point he must know how high the granite cliff is above their beach, and he finds it with nothing but a straight pole stuck in the sand and the rule of similar triangles: the small triangle is to the large triangle as the pole is to the cliff.

I read that chapter four times. Then I went out with a broom handle and a measuring tape borrowed from my mother's sewing box, and I measured the bell tower of the cathedral.

It was the method of the shadows, which I found later was older than Verne by more than two thousand years. At ten in the morning, in the square, I stood the broom handle upright and measured its shadow on the paving stones. Then I paced the shadow of the tower, which took some time, because the shadow fell across the street and people kept walking through my measurements and asking what I was doing. Then I sat on the edge of a bench with a pencil stub and made the proportion. I do not remember the number I got. I remember the feeling exactly. It was the feeling of having reached up and touched the top of a building I could never climb, using only my head.

I ran home and told my father. He did not say "very good," as most fathers would have. He asked me how I knew the broom handle was straight up. I said I had looked at it. He asked how I knew the ground was level. I had no answer. The next Saturday he brought home a small brass plumb bob from the warehouse, the kind carpenters use, on a length of string, and gave it to me without a word. I measured the tower again. I had been off by nearly a meter the first time.

That was my father's way. He did not praise; he asked the next question. I have tried for fifty years to teach like that, and I have only sometimes succeeded, because it is much easier to say "very good."

I should not give the impression that I was a boy who did nothing but read and measure. I swam in the bay like every boy in Cienfuegos, off the rocks along the Malecón, the seawall, and I was not a strong swimmer but I was a stubborn one. On Sundays the families walked along the Prado under the trees, the girls in one direction and the boys in the other, so that everyone could look at everyone twice. When the circus came, I went to the circus. In the summers we sometimes took the little boat across the bay to visit my mother's sister, who lived near the fishing villages on the other side, and I learned to clean a fish, badly, and to sleep in a hammock, well.

On the southern point of the city, at Punta Gorda, a rich man had built a palace in the Moorish style, all arches and colored tiles and little towers, like something from The Thousand and One Nights. My friends and I would walk out to look at it from the street. The other boys wanted to know how much it had cost. I wanted to know how they had made the arches stand up. These are, I suppose, the two kinds of people.

At school I had a teacher in the fifth grade, a severe man who wore a white suit every day of the year and carried a gold fountain pen, who called me to his desk one afternoon after I had finished an examination too quickly. I thought I was in trouble. Instead he gave me a problem he had written on a card, a problem about two trains, which I could not do. He told me to bring it back when I could. It took me nine days. When I brought it back, he gave me another card. By the end of that year I had a stack of them tied with string, and I have them still, in a cigar box in my closet in Miami. They are among the things that came out of Cuba in my one suitcase. I will explain about the suitcase in the next chapter.

My mother worried that I would ruin my eyes. My father worried, I think, that I would be a bookkeeper, like him, and he wanted something more for me without being able to say exactly what. When I finished the bachillerato, the secondary diploma, in 1943, and was accepted to study mathematics at the University of Havana, he was so proud that he could not speak at the railway station. He shook my hand like a man, and then he took a parcel from under his arm and gave it to me, and walked away down the platform before the train had even begun to move.

In the parcel was a new copy of La isla misteriosa, in a better binding than our old one, which by then had lost its cover. Inside it he had written, in his beautiful bookkeeper's hand: Para que midas cosas más altas. So that you may measure taller things.

I read it on the train to Havana, all through the night. It is on the shelf beside me as I write this. Its binding, too, has seen better days.