‘And I remember that when I asked our famous Harvey in the only Discourse I had with him, (which was but a while before he dyed) What were the things that induc'd him to think of a Circulation of the Blood? He answer'd me, that when he took notice that the Valves in the Veins of so many several Parts of the Body, were so Plac'd that they gave free passage to the Blood Towards the Heart, but oppos'd the passage of the Venal Blood the Contrary way: He was invited to imagine, that so Provident a Cause as Nature had not so Plac'd so many Valves without Design: and no Design seem'd more probable, than That, since the Blood could not well, because of the interposing Valves, be Sent by the Veins to the Limbs; it should be Sent through the Arteries, and Return through the Veins, whose Valves did not oppose its course that way.’ (Robert Boyle, A Disquisition about the Final Causes of Natural Things, London, 1688, pp. 157–8.)

BIBLIOGRAPHICAL PREFACE

HARVEY'S first and greatest work, usually known by its short title of De Motu Cordis, was printed in 1628, but his interest in the subject of the circulation of the blood was doubtless initiated by his association with Fabricius ab Aquapendente during his studentship at the University of Padua in the years 1598 to 1602. It was here that he first became acquainted with his teacher's observations on valves in veins, and it was from these that his own observations and experiments ultimately deduced the facts of the circulation of the blood. ‘Harvey's common designation of discoverer of the circulation of the blood suggests that he stumbled suddenly and unexpectedly upon the truth. But Harvey, like other scientific investigators, found no short cut to knowledge. His mind had the acuteness necessary to perceive the inconsistencies which had escaped his predecessors, and he possessed the patience and scientific imagination to piece together the innumerable observations that he had made, both while treating his patients and while dissecting and experimenting on animals’.