An idea conceived by Yang in 1953 was developed with the assistance of a doctoral student, Robert Mills, with whom he was sharing an office during a visit to Brookhaven National Laboratory on Long Island, New York. This brief encounter led to Mills becoming immortalised by inclusion in the moniker “Yang-Mills theories”. Today Yang-Mills theories underpin fundamental particle physics, successfully describing the weak and the strong nuclear forces. Initially, however, the reaction of the acerbic theorist Wolfgang Pauli was so damning that Yang’s nascent career was in jeopardy.