On October 18, 1879, a young inventor by the name of Thomas A. Edison sat in his laboratory. He was weary from 13 months of repeated failure in his search for a filament that would stand the stress of electric current. To add to his problems, the men who had backed him financially were now refusing to put up any additional funds. Having tried every known metal in his experiment, Edison was admittedly baffled. Casually picking up a bit of lampblack, he mixed it with tar and rolled in into a thin thread. Suddenly the thought struck him, why not try a carbonized cotton fiber? For 5 hours he worked on the first filament, but it broke before he could remove the mold. Two entire spools of thread were used in similar fruitless efforts. At last a perfect strand emerged, only to be ruined when he tried to place it inside a glass tube. Still Edison refused to admit defeat. He continued to work without sleep for two more days and nights. Eventually he managed to insert one of the crude carbonized threads into a vacuum-sealed bulb. "When he turned on the current," he said, "the sight we had so long desired to see finally met our eyes!" His persistence in the face of the most discouraging odds gave the world one of its greatest inventions - the electric light!