He made a line on the blackboard, one bold stroke from right to left diagonally downward and stood back to ask, looking as always at no one in particular, "What have I done?" From the back of the room Freddie shouted, "You've broken a piece of chalk." M. Degas did not smile. "What have I done?" he repeated. The most intellectual students looked down to study their desks except for Gertrude Bimmler, who raised her hand before she spoke. "M. Degas, you have created the hypotenuse of an isosceles triangle." Degas mused. Everyone knew that Gertrude could not be incorrect. "It is possible," Louis Warshowsky added precisely, "that you have begun to represent the roof of a barn." I remember that it was exactly twenty minutes past eleven, and I thought at worst this would go on another forty minutes. It was early April, the snow had all but melted on the playgrounds, the elms and maples bordering the cracked walks shivered in the new winds, and I believed that before I knew it I'd be swaggering to the candy store for a Milky Way. M. Degas pursed his lips, and the room stilled until the long hand of the clock moved to twenty one as though in complicity with Gertrude, who added confidently, "You've begun to separate the dark from the dark." I looked back for help, but now the trees bucked and quaked, and I knew this could go on forever.