Pyotr Tchaikovsky composed and conducted his final symphony in 1893. He died 9 days later, after having knowingly drunk an unboiled glass of water during a cholera epidemic. Deep into the symphony, Symphony no. 6, there is a paradoxical passage that, when played, no one will be able to hear.  This is because Tchaikovsky scored it to contain a musical illusion. We uncover the mystery of why he put it there. Sound illusions reveal some of the most puzzling features of the human mind, most notably its insistence that it knows reality better than reality itself. On this episode, we listen to some of the most curious auditory illusions to find out how some of the features of sounds are generated by the human mind, rather than features of the external world. The illusions reveal something deep about some of the most treasured human endeavors, including music and language.Guest voices include Diana Deutsch, Casey O'Callaghan, and Christine Howlett. Thanks to Kenna Tuggle for violin passages. Get $50 off your first job post at LinkedIn Talent Solutions. Go to linkedin.com/nation.