Willis was born on his parents' farm in
Great Bedwyn,
Wiltshire, where his father held the stewardship of the manor. He was a kinsman of the
Willys baronets of
Fen Ditton, Cambridgeshire. He graduated
M.A. from
Christ Church, Oxford in 1642. In the Civil War years he was a
Royalist, dispossessed of the family farm at
North Hinksey by
Parliamentary forces. In the 1640s, Willis was one of the royal physicians to
Charles I. Once qualified B. Med. in 1646, he began as an active physician by regularly attending the market at
Abingdon,
Oxfordshire. Fell's father
Samuel Fell had been expelled as
Dean of Christ Church in 1647; Willis married Samuel Fell's daughter Mary, and his brother-in-law John Fell would later be his biographer. He employed
Robert Hooke as an assistant, in the period 1656–8; this probably was another Fell family connection, since Samuel Fell knew Hooke's father in
Freshwater, Isle of Wight. One of several Oxford cliques of those interested in science grew up around Willis and Christ Church. Besides Hooke, others in the group were
Nathaniel Hodges,
John Locke,
Richard Lower,
Henry Stubbe and
John Ward. (Locke went on to study with
Thomas Sydenham, who would become Willis's leading rival, and who both politically and medically held some incompatible views). In the broader Oxford scene, he was a colleague in the "
Oxford club" of experimentalists with
Ralph Bathurst,
Robert Boyle,
William Petty,
John Wilkins and
Christopher Wren. Willis was on close terms with Wren's sister Susan Holder, skilled in the healing of wounds. He and Petty were among the physicians involved in treating
Anne Greene, a woman who survived her own hanging and was pardoned because her survival was widely held to be an act of
divine intervention. The event was widely written about at the time, and helped to build Willis's career and reputation. Willis lived on
Merton Street,
Oxford, from 1657 to 1667. In 1656 and 1659 he published two significant medical works,
De Fermentatione and
De Febribus. These were followed by the 1664 volume on the brain, which was a record of collaborative experimental work. From 1660 until his death, he was
Sedleian Professor of Natural Philosophy at Oxford. At the time of the formation of the
Royal Society of London, he was on the 1660 list of priority candidates, and became a Fellow in 1661. Henry Stubbe became a polemical opponent of the Society, and used his knowledge of Willis's earlier work before 1660 to belittle some of the claims made by its proponents. Willis later worked as a physician in
Westminster, London, this coming about after he treated
Gilbert Sheldon in 1666. According to Noga Arikha: Among his patients was the philosopher
Anne Conway, with whom he had intimate relations, but although he was consulted, Willis failed to relieve her headaches. Willis is mentioned in
John Aubrey's
Brief Lives; their families became linked generations later through the marriage of Aubrey's distant cousin
Sir John Aubrey, 6th Baronet of
Llantrithyd to Martha Catherine Carter, the grand-niece of Sir William Willys, 6th
Baronet of
Fen Ditton. ==Research activity==