during childhood and recurring untreated middle-ear infections. He subsequently concocted elaborate fictitious stories about the cause of his deafness. As he was completely deaf in one ear and barely hearing in the other, it is alleged that Edison would listen to a music player or piano by clamping his teeth into the wood to absorb the sound waves into his skull. As he got older, Edison believed his hearing loss allowed him to avoid distraction and concentrate more easily on his work. Modern-day historians and medical professionals have suggested he may have had ADHD. It is known that early in his career he enrolled in a chemistry course at The Cooper Union for the Advancement of Science and Art to support his work on a new telegraphy system with Charles Batchelor. This appears to have been his only enrollment in courses at an institution of higher learning. Early career Thomas Edison began his career as a news butcher, selling newspapers, candy and vegetables on the trains running from Port Huron to Detroit. He turned a $50-a-week profit by age 13, most of which went to buying equipment for electrical and chemical experiments. At age 15, in 1862, he saved 3-year-old Jimmie MacKenzie from being struck by a runaway train. Jimmie's father, station agent J. U. MacKenzie of Mount Clemens, Michigan, was so grateful that he trained Edison as a telegraph operator. Edison's first telegraphy job away from Port Huron was at Stratford Junction, Ontario, on the Grand Trunk Railway. He also studied qualitative analysis and conducted chemical experiments until he left the job rather than be fired after being held responsible for a near collision of two trains. Edison obtained the exclusive right to sell newspapers on the road, and, with the aid of four assistants, he set in type and printed the Grand Trunk Herald, which he sold with his other papers. This began Edison's long streak of entrepreneurial ventures, as he discovered his talents as a businessman. Ultimately, his entrepreneurship was central to the formation of some 14 companies, including General Electric, formerly one of the largest publicly traded companies in the world. In 1866, at the age of 19, Edison moved to Louisville, Kentucky, where, as an employee of Western Union, he worked the Associated Press bureau news wire. Edison requested the night shift, which allowed him plenty of time to spend at his two favorite pastimes—reading