Before Andrés Segovia, the classical guitar was a quiet parlor novelty. By the time he died in Madrid at 94, it was a centerpiece of the world’s grandest concert halls, and he was a Marquis with an asteroid named after him. This episode follows the self-taught Spanish rebel whose family wanted him to be a lawyer, whose first violin lessons were a joyless disaster, and who rejected the flamenco all around him in Granada to hunt down classical works by Sor and Tárrega.

We break down the physics of his heretical technique, plucking with fingernails near the bridge to fill 3,000-seat halls, and the three-pronged strategy he used to build a repertoire from scratch: transcribing Bach’s Chaconne, editing and reviving older guitar composers, and commissioning new works from Ponce, Villa-Lobos, and Castelnuovo-Tedesco. Then we confront the paradox of his later years, when the rule-breaker became a dogmatic gatekeeper who, according to student John Williams, bullied pupils and rejected atonal pieces written for him.

• How Tárrega’s death before a single lesson forced Segovia to become both professor and pupil
• Why Madrid critics in 1912 called his fingernail tone harsh and metallic
• The debate over whether nylon strings and recording technology made his career or merely amplified it
• His 1928 U.S. debut, Grammy honors, ten honorary doctorates, and elevation to the Spanish nobility in 1981
• Whether the conservatory system he built makes another self-taught innovator impossible