The word appears around 1907, and the system everyone uses was constructed by Mrs. L. Dow Balliett, born Sarah Joanna Dennis, 1847 to 1929. Her books, How to Attain Success Through the Strength of Vibration (1905) and The Philosophy of Numbers (1908), fixed the English A=1 to I=9 letter grid, the birth-number versus name-number split, and the vowels-as-soul reading. Her student Juno Jordan ran the California Institute of Numerical Research for some 25 years, formalizing the rest. Nothing in the record shows Pythagoras reducing names to digits.
The story Balliett inherited is genuinely old: Pythagoras declaring all is number, his school swearing oaths on the Tetractys, ten dots in a triangle; Nicomachus cataloguing number meanings around 100 CE; Boethius carrying it into every medieval university; Agrippa's 1533 synthesis mapping each number across angels, planets, elements, and soul. Balliett translated Agrippa's 6, the most perfect number in nature, into her Cosmic Mother, and his 7 into her Finished Number, a complete temple standing alone. She claimed to hear the music of the spheres once, on an overnight train.
The claim, held since Croton: number is not a description of the universe but its substance, all is number meant literally, so reducing your name to a digit reads your entry in the cosmic register. The mathematician Underwood Dudley's counter is the archive's favorite line on the subject: numbers have power, but the power is not over events, it is over human minds.
If the system is a century old but the meanings are two thousand years old, which date is the real origin?