Feluda stopped reading and shut his book with a bang. Then he snapped his fingers twice, yawned heavily and said, ‘Geometry.’ I asked, ‘Were you reading a book on geometry all this while?’ The book was covered with newspaper, so I could not see its title. All I knew was that Feluda had borrowed it from Uncle Sidhu, who was passionate about books. He bought quite a few, and took great care of them. In fact, he did not like lending his books to anyone, but Feluda was an exception. Feluda knew it, so he always put a protective cover on any book that he brought from Uncle Sidhu’s house. Feluda lit a Charminar and blew out two smoke rings, one after the other. ‘There is no such thing as a book on geometry,’ he told me. ‘Any book may be seen as one because everything around us is related to geometry. Did you see those smoke rings? When they left my mouth, they were perfect circles. Now just think. There are circles everywhere. Look at your own body. The iris in your eye is a circle. With the help of the iris, you can look at the sun and the moon. If you think of them as flat objects, they are circles, but of course they are actually spheres—each a solid bubble. That’s geometry. The planets in the solar system are orbiting the sun in elliptic curves. There’s geometry again. When you spat out of the window a little while ago—you shouldn’t have done that, it’s most unhygienic and if you do it again, you’ll get a sharp rap on the head, but anyway—that spit went out in a parabolic curve. Geometry, see? Have you ever looked at a spider’s web in any detail? It starts with a simple square. Then two diagonal lines run through it and the square is divided into four triangles. After that, the spider starts weaving a spiral web from the intersecting point of those diagonal lines. That keeps growing in size, until it covers the entire square. If you think about it, your head will start reeling . . . it’s something so amazing!’ It was a Sunday morning. The two of us were sitting in our living room on the ground floor. Baba had gone to visit his childhood friend, Subimal, as he did every Sunday. Feluda was seated on a sofa, his feet resting on a low table. I was on a divan, leaning on a cushion placed against the wall. In my hand was a game. It was a maze, made of plastic. Inside the maze were tiny metal balls. Over the last half hour, I had been trying to make those metal balls slip through the various lanes in the maze and go straight to its centre. Now I realized that the game was a matter of complex geometry, too. A Durga Puja was being held in Nihar and Pintu’s house, which was near ours. Someone was playing a