Franciscus Sylvius (1614-1672), also known as Franz De Le Boe, was physician and scientist (chemist, physiologist and anatomist). He was born in Hanau, Germany but worked and died in Holland. In 1658 he was appointed the professor of medicine at the University of Leyden and was paid 1800 guilders which was twice the usual salary. He was the University's Vice-Chancellor in 1669-70. He founded the Iatrochemical School of Medicine, according to which all life and disease processes are based on chemical actions. That school of thought attempted to understand medicine in terms of universal rules of physics and chemistry. Sylvius also introduced the concept of chemical affinity as a way to understand the way the human body uses salts and contributed greatly to the understanding of digestion and of bodily fluids. The most important work he published was, "Praxeos medicae idea nova, 1671" (New idea in medical practice). His collected works were published in 1671. He was one of the earliest defenders of the circulation of the blood in Holland.

He researched the structure of the brain and discovered the cleft in the brain now known as Sylvius' fissure. Sylvius' angle is also named after him.

References

• Sylvian fissure
• Underwood, E. A. Franciscus Sylvius and his iatrochemical school. Endeavor, 1972 (May), 31(113), 73-76.
• Sylvius, Franciscus dele Bo
• History of Alcohol and Drinking Around the World