Directions: The short passage below is followed by a question based on its content. Answer the question on the basis of what is stated or implied in the passage. Thomas Alva Edison lit up the world with his invention of the electric light. Without him, the world might still be a dark place. However, the electric light was not his only invention. He also invented the phonograph, the motion picture camera, and over 1,200 other things. About every two weeks he created something new. When he was 12 years old, he got his first job. He became a newsboy on a train that ran between Port Huron and Detroit. He set up a laboratory in a baggage care of the train so that he could continue his experiments in his spare time. Unfortunately, his first work experience did not end well. Thomas was fired when he accidentally set fire to the floor of the baggage car. Thomas then worked for five years as a telegraph operator, but he continued to spend much of his time on the job conducting experiments. He got his first patent in 1868 for a vote recorder run by electricity. However, the vote recorder was not a success. In 1870, he sold another invention, a stock-ticker, for $40,000. Thomas Edison was totally deaf in one ear and hard of hearing in the other, but thought of his deafness as a blessing in many ways. It kept conversations short, so that he could have more time for work. He called himself a “two-shift man” because he worked 16 out of every 24 hours.

What is the theme of the passage?