Thomas Alva Edison tried two thousand different materials in search of a filament for the light bulb. When none worked satisfactorily, his assistant complained, “All our work is in vain. We have learned nothing.” Edison replied very confidently, “Oh, we have come a long way and we have learned a lot. We know that there are two thousand elements which we cannot use to make a good light bulb.” After many experiments with platinum and other metal filaments, Edison returned to a carbon filament.[inconsistent] The first successful test was on October 22, 1879; it lasted 13.5 hours. Edison made the first public demonstration of his incandescent light bulb on December 31, 1879, in Menlo Park. It was during this time that he said: "We will make electricity so cheap that only the rich will burn candles."