[Willis and his circle].

Thomas Willis (1621-1675) grew up in Wiltshire and studied medicine in Oxford, at a time when the city was besieged and then occupied by Parliamentarian troops. He started his career as a country doctor while concurrently taking part in informal gatherings with other scientists (William Petty, Christopher Wren and, later on, Robert Hooke, Richard Lower and Robert Boyle). They performed physical and chemical experiments and carried out a variety of tests on animals. After the restoration of the monarchy in 1660 Willis combined his practice with academic teaching. From then on he focused his studies on the structure and function of the brain, dissecting brains after removal from the skull and fixation in 'spirit of wine'. In his 'Cerebri anatome' of 1664, illustrated by Wren, he drew attention to the arterial circle at the base of the brain, including its physiological advantages. This arterial circle had been incompletely described by others in the past and fully, but only in writing, by Wepfer in 1658.