who is considered to be the most influential writer of all time on medical subjects
Galen Aelius Galenus or Claudius Galenus (/ɡəˈliːnəs/;[1] Greek: Κλαύδιος Γαληνός; September 129 AD – c. 200/c. 216), often Anglicized as Galen and better known as Galen of Pergamon (/ˈɡeɪlən/),[2] was a prominent Greek physician, surgeon and philosopher in the Roman Empire.[3][4][5] Arguably the most accomplished of all medical researchers of antiquity, Galen influenced the development of various scientific disciplines, including anatomy,[6] physiology, pathology,[7] pharmacology,[8] and neurology, as well as philosophy[9] and logic.
John Snow John Snow (15 March 1813 â€“ 16 June 1858) was an English physician and a leader in the adoption of anaesthesia and medical hygiene. He is considered one of the fathers of modern epidemiology, in part because of his work in tracing the source of a cholera outbreak in Soho, London, in 1854. His findings inspired fundamental changes in the water and waste systems of London, which led to similar changes in other cities, and a significant improvement in general public health around the world.