Even centuries later, there remains one big mystery about Ludwig van Beethoven’s life: When is his birthday? Though his last words were well recorded when he died on Mar. 26, 1827, the other end of his life was much more obscure. The date of his birth is often supposed to be Dec. 16, 1770, and his baptism was on the following day—245 years ago Thursday.

But there’s a lot we do know about Beethoven, and one of the most commonly known facts is that, by the end of his life, the world’s most famous musical genius couldn’t hear his own work.

Interest in Beethoven’s hearing loss has long captivated his fans, many of whom are fascinated by the tragic circumstances of a deaf composer and the ways Beethoven managed to keep working even after he completely lost his hearing by the time he was 45. As TIME once described it, “by clenching a stick in his teeth, holding it against the keyboard of his piano, he could discern faint sounds.”

He even introduced the world to what remains perhaps his most famous composition—the Ninth Symphony—well after deafness had overtaken him, an irony that produced one of the most poignant moments of his career, as TIME noted in 1932:

Three years before Ludwig van Beethoven shook his great fist at the thunder & lightning raging outside his window and fell back dead on his bed, his Ninth (last) Symphony was given its first performance in Vienna. Beethoven, a homely, dumpy, shaggy-headed little figure, stood in the orchestra, eyes fixed on his score, awkwardly beating time. He was not the official conductor. The players had been instructed to pay him no attention. He was so deaf by that time that he could hear nothing of the great, surging music called for by the pinny, almost illegible little notes he had made. He did not sense the applause which came afterwards until one of the soloists, a Fraulein Caroline Unger, turned him around so that his eyes could take it in. The music passed into the background then. The demonstration took a sudden, emotional turn as the people started shouting, beating their palms together still harder in an effort to assure the fierce-looking little man of their sympathy, their appreciation.

That appreciation did nothing to lift the melancholy that had settled on Beethoven by then. Though he would joke about his other ailments, his letters later revealed to the world that his hearing problems only left him depressed, isolated from society and afraid that he was being taken advantage of. “My poor hearing haunted me everywhere like a ghost; and I have avoided all human society,” he once wrote. “I seem a misanthrope and yet am far from being one.”

Yet his hearing loss and the way he coped with it in daily life has helped preserve his story for the ages.

Because he used a notebook to conduct conversations with friends, family and colleagues, the written records of those conversations could be maintained. The transcripts are often one-sided, as he would still respond to many questions verbally, but “they make clear what Beethoven was thinking about,” TIME noted when the ‘conversation notebooks’ were released in the 1970s, “and where he occasionally wrote in the books himself—usually for a comment that he did not want others in the room to overhear—the blunt style is unmistakable. Nephew Karl brings home a somewhat seedy friend, and Beethoven jots down: ‘I don’t like your choice of this friend at all. Poverty deserves sympathy, but not without exceptions.'”

In the 1990s, a few American fans of his purchased a lock of Beethoven’s hair at an auction for the purpose of examining the medical data preserved within, hoping to find out once and for all whether his deafness was really, as had been long supposed, caused by use of mercury as treatment for syphilis. That lock of hair is kept at San José State University, and as of 2000 no tell-tale mercury had been found.

Read more about Beethoven’s birthday: You Have to Try This Google Doodle Honoring Ludwig van Beethoven

Read an assessment of Beethoven on the 200th anniversary of his death, here in the TIME Vault: 200-Condlepower

Get our History Newsletter. Put today's news in context and see highlights from the archives. Please enter a valid email address. Sign Up Now Check the box if you do not wish to receive promotional offers via email from TIME. You can unsubscribe at any time. By signing up you are agreeing to our Terms of Use and Privacy Policy . This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. Thank you! For your security, we've sent a confirmation email to the address you entered. Click the link to confirm your subscription and begin receiving our newsletters. If you don't get the confirmation within 10 minutes, please check your spam folder.

Write to Lily Rothman at lily.rothman@time.com.