Howard Florey is best known as the scientist who developed penicillin and ushered in the modern antibiotic era. As an experimental pathologist he founded one of the leading schools of experimental pathology at Oxford and his achievements established him as one of the foremost medical scientists of the twentieth century. Florey's ambition and drive toward medical research commenced in the years 1922-1925 when he was a Rhodes scholar at Oxford. His mentor was the neurophysiologist and Nobel Laureate, Sir Charles Sherrington who directed him in neuroscience research. Florey's initial studies on the cerebral circulation represent an original contribution to medical knowledge and highlight his remarkable scientific method. The mentorship and close personal relationship with Sherrington was a crucial factor in Florey's early research career.