I remember once listening to some tedious Galenist lecturing on blood in Padua and the very next day being lent a copy of Harvey’s magnificent work on circulation. It was so clear, so simple, and so obviously true that it took my breath away. I have not had an experience like it since. However, even I could see that it was incomplete. Harvey demonstrated that the blood starts in the heart, circulates around the body, then returns whence it came. He did not establish why it does this, and without that science is a poor thing.

Iain Pears – An Instance Of The Fingerpost