Reread to Understand

How Braille Was Invented

Louis Braille was blinded in an accident at the age of three. At his school, blind pupils read by tracing raised letters pressed into paper. It worked, slowly — a fingertip cannot take in a whole letter shape at once — and nobody could write that way at all. When Braille was twelve, a soldier visited the school with a code of raised dots that soldiers used to read messages in the dark. It was too complicated, but the idea of dots was right. Braille spent three years simplifying it. He settled on a cell of six dots, small enough to sit under one fingertip. He was fifteen when he finished. He was forty-three when he died, and the system was not widely accepted until after that.

Why Bread Rises

Yeast is alive. It is a fungus, and each grain of dried yeast holds millions of cells waiting for water. Add warm water and the cells wake up. They begin to feed on the sugars in the flour. As they feed, they give off carbon dioxide gas. The gas cannot escape, because kneading the dough has built a stretchy web of gluten that traps it. Thousands of tiny bubbles form, and the dough swells. In the oven, two things happen. The trapped gas expands in the heat, so the loaf rises further. Then the heat kills the yeast and sets the gluten, and the bubbles are locked in place. That is why bread has holes in it.