‘Do you know why the sight of trees and plants have such a refreshing effect on our eyes?’ asked Feluda. ‘The reason is that people, since primitive times, have lived with greenery all around them, so that their eyes have developed a healthy relationship with their environment. Of course, trees in big cities these days have become rather difficult to find. As a result, every time you get away from town, your eyes begin to relax, and so does your mind. It is mostly in cities that you’ll notice people with eye disorders. Go to a village or a hill-station, and you’ll hardly find anyone wearing glasses.’ Feluda himself had a pair of sharp eyes, didn’t wear glasses, and could stare at any object for three minutes and fifteen seconds without blinking even once. I should know, for I had tested him often enough. But he had never lived in a village. I was tempted to point this out to him, but didn’t dare. The chances of having my head bitten off if I did were very high. We were travelling with a man called Monimohan Samaddar. He wore glasses (but then, he lived in a city), was about fifty years old and had sharp features. The hair around his ears had started to turn grey. It was in his Fiat that we were travelling, to a place called Bamungachhi, which was a suburb of Calcutta. We had met Moni Babu only yesterday. He had turned up quite out of the blue in the afternoon, as Feluda and I sat in our living room, reading. I had been watching Feluda reading a book on numerology, raising his eyebrows occasionally in both amazement and appreciation. It was a book about Dr Matrix. Feluda caught me looking at him, and smiled. ‘You’d be astonished to learn the power of numbers, and the role they play in the lives of men like Dr Matrix. Listen to this. It was a discovery Dr Matrix made. You know the names of the two American Presidents who were assassinated, don’t you?’ ‘Yes. Lincoln and Kennedy, right?’ ‘Right. Now tell me how many letters each name has.’ ‘L-i-n-c-o-l-n—seven. K-e-n-n-e-d-y—also seven.’ ‘OK. Now listen, carefully. Lincoln was killed in 1865 and Kennedy died in 1963, a little less than a hundred years later. Both were killed on a Friday, and both had their wives by their side. Lincoln was killed in the Ford Theatre. Kennedy was killed in a car called Lincoln, manufactured by the Ford company. The next President after Lincoln was called Johnson, Andrew Johnson. Kennedy was succeeded by Lyndon Johnson. The first Johnson was born in 1808, the second in 1908, exactly a hundred years later. Do you know who killed Lincoln?’ ‘Yes, but I can’t remember his name right now.’ ‘It was John Wilkes Booth. He was born in 1839. And Kennedy was killed by Lee Harvey Oswald. He was born in 1939! Now count the number of letters in both names.’ ‘Good heavens,