The development of modern neurosurgery in the Netherlands, which took place in the 1920s, was highly influenced by the personal involvement of both Harvey Cushing and Walter Dandy, each in his own way. For the present article, the authors consulted the correspondence (kept at the Cushing/Whitney Medical Library in New Haven and the Alan Mason Chesney Medical Archives in Baltimore) of Cushing and Dandy with their Dutch disciples. The correspondence provides a unique inside view into the minds of both neurosurgical giants. After the neurologist Bernard Brouwer had paved the way for sending the Dutch surgeon Ignaz Oljenick overseas, Cushing personally took the responsibility to train him (1927-1929). On his return to Amsterdam, Oljenick and Br...