Sir William Osler, 1st Baronet (; July 12, 1849 – December 29, 1919) was a Canadian physician and one of the "Big Four" founding professors of Johns Hopkins Hospital. Osler created the first residency program for specialty training of physicians. He has frequently been described as the Father of Modern Medicine and one of the "greatest diagnosticians ever to wield a stethoscope". In addition to being a physician he was a bibliophile, historian, author, and renowned practical joker. He was passionate about medical libraries and medical history, having founded the History of Medicine Society (formally "section"), at the Royal Society of Medicine, London. He was also instrumental in founding the Medical Library Association of Great Britain and Ireland, and the (North American) Association of Medical Librarians (later the Medical Library Association) along with three other people, including Margaret Charlton, the medical librarian of his alma mater, McGill University. He left his own large history of medicine library to McGill, where it became the Osler Library.
William Osler's great-grandfather, Edward Osler, was variously described as either a merchant seaman or a pirate. One of William's uncles, Edward Osler (1798–1863), a medical officer in the Royal Navy, wrote the Life of Lord Exmouth and the poem The Voyage.
William Osler's father, the Reverend Featherstone Lake Osler (1805–1895), the son of a shipowner at Falmouth, Cornwall, was a former lieutenant in the Royal Navy who served on HMS Victory. In 1831, Featherstone Osler was invited to serve on HMS Beagle as the science officer for Charles Darwin's historic voyage to the Galápagos Islands, but he turned it down because his father was dying. In 1833, Featherstone Osler announced that he wanted to become a minister of the Church of England.
As a teenager, Featherstone Osler was aboard HMS Sappho when it was nearly destroyed by Atlantic storms and remained adrift for weeks. Serving in the Navy, he was shipwrecked off Barbados. In 1837, Featherstone Osler retired from the Navy and emigrated to Canada, becoming a "saddle-bag minister" in rural Upper Canada. When Featherstone and his bride, Ellen Free Picton, arrived in Canada, they were nearly shipwrecked again on Egg Island in the Gulf of Saint Lawrence. Their children included William, Britton Bath Osler and Sir Edmund Boyd Osler.
William Osler was born in Bond Head, Canada West (Ontario), on July 12, 1849, and raised after 1857 in Dundas, Ontario. He was named William after William of Orange, who won the Battle of the Boyne on July 12, 1690. Osler's mother, who was very religious, prayed that he would become a priest. Osler was educated at Trinity College School (then located in Weston, Ontario).
In 1867, Osler announced that he would follow his father's footsteps into the ministry and entered Trinity College of the University of Toronto, in the autumn. However, he became increasingly interested in medical science under the influence of James Bovell and the Rev. William Arthur Johnson, encouraging him to switch his career.
In 1868, Osler enrolled in the Toronto School of Medicine, a privately owned institution that was not part of the Medical Faculty of the University of Toronto. Osler lived with James Bovell for a time, and through Johnson, he was introduced to the writings of Sir Thomas Browne; his Religio Medici caused a deep impression on him.
Osler left the Toronto School of Medicine after being accepted into the MDCM program at the McGill University Faculty of Medicine in Montreal in 1870. Osler received his medical degree (MDCM) in 1872.
While studying at McGill, Osler lived on lower Saint Urbain Street, at a time when the medical school was on nearby Côté Street. While in Montreal, Osler, who was a practicing Anglican regularly attended the "free seat" Chapel of St. John the Evangelist which at the time was located on Dorchester Street (now René Lévesque Boulevard). Osler held the chapel's rector, Fr. Edmund Wood in high regard due to his care for the less fortunate. Osler had personal copies of the 1662 Book of Common Prayer and Hymns Ancient and Modern, both of which are kept in the Osler Library of the History of Medicine at McGill. Osler and Fr. Wood would later on contribute to the installation of a memorial stained glass window in honour of Rev. Dr. William Wright, a professor of Materia medica at the McGill Faculty of Medicine and also a long time associate priest at the Church of St. John the Evangelist, which had since built a new church building on Ontario Street (now President Kennedy Avenue) and Saint Urbain, a few blocks north of the chapel's former location.
Following post-graduate training under Rudolf Virchow in Germany, Osler returned to the McGill University Faculty of Medicine as a professor in 1874. There he created the first formal journal club, showed interest in comparative pathology, and is considered the first to have taught veterinary pathology in North America as part of a broad understanding of disease pathogenesis. In 1884, he was appointed Chair of Clinical Medicine at the University of Pennsylvania in Philadelphia and in 1885, was one of the seven founding members of the Association of American Physicians, a society dedicated to "the advancement of scientific and practical medicine." When he left Philadelphia in 1889, his farewell address, "Aequanimitas", was about the imperturbability (calm amid storm) and equanimity (moderated emotion, tolerance) necessary for physicians.
In 1889, he became the first Physician-in-Chief of the new Johns Hopkins Hospital in Baltimore, Maryland. In 1893, Osler was instrumental in creating the Johns Hopkins School of Medicine and became one of the school's first professors of medicine. Osler quickly enhanced his reputation as a clinician, humanitarian, and teacher. He presided over the rapidly expanding hospital's first year of operation, when it had 220 beds and 788 patients were seen for a total of over 15,000 days of treatment. Sixteen years later, when Osler left for Oxford, over 4,200 patients were seen for a total of nearly 110,000 days of treatment.
In 1905, he was appointed to the Regius Professor of Medicine at Oxford, which he held until his death. He was also a Student (fellow) of Christ Church, Oxford.
In the UK, he initiated the founding in 1907 of the Association of Physicians and was founding Senior Editor of its publication the Quarterly Journal of Medicine until his death.
In 1911, he founded the Postgraduate Medical Association and was its first President. The same year, Osler was named a baronet in the Coronation Honours List for his contributions to the field of medicine.
In January 1919 he was appointed President of the Fellowship of Medicine and was in October appointed founding President of the merged Fellowship of Medicine and Postgraduate Medical Association, which became the Fellowship of Postgraduate Medicine.
The largest collection of Osler's letters and papers is at the Osler Library of McGill University in Montreal and a collection is also held at the United States National Library of Medicine in Bethesda, Maryland.
Perhaps Osler's greatest influence on medicine was to insist that students learn from seeing and talking to patients and the establishment of the medical residency. The latter idea spread across the English-speaking world and remains in place today in most teaching hospitals. Through this system, physicians in training make up much of a teaching hospital's medical staff. The success of his residency system depended, in large part, on its pyramidal structure with many interns, fewer assistant residents and a single chief resident, who originally occupied that position for years. While at Hopkins, Osler established the full-time, sleep-in residency system whereby staff physicians lived in the administration building of the hospital. As established, the residency was open-ended, and long tenure was the rule. Physicians spent as long as seven or eight years as residents, during which time they led a restricted, almost monastic life.