Who was William Harvey?
Harvey was a doctor at St. Bartholomew's hospital in London and a Fellow of the Royal College of Physicians. He was also the physician to James I and Charles I. Harvey studied in Italy at the University of Padua where he became interested in anatomy and in particular, the work of Vesalius.

What were his important discoveries?
In 1615 Harvey began to work on the idea that blood circulated around the body. By experimenting on live animals and dissecting the bodies of executed criminals, Harvey was able to prove that the heart was a pump which forced blood around the body through arteries. Veins then returned the blood to the heart where it was recycled. Harvey's work was helped by the discovery that veins contained valves. Harvey realised that these valves stopped the blood from travelling back the wrong way to the heart. Galen's theory (that the body made new blood as its supplies were used up) was proved wrong. In 1628, Harvey published details of his work in his book entitled 'An Anatomical Disquisition on the Movement of the Heart and Blood.'

Why did Harvey face opposition?
After his work was published, Harvey actually lost patients, as his ideas were considered eccentric. It was not until after his death that others became convinced that he was right. Marcello Malpighi (1628-1694), an Italian physician, used better quality microscopes to prove that Harvey's ideas were correct.