[From Hippocrates to Harvey: twenty centuries of research on circulation]

The concept of blood circulation was difficult to emerge. By assessing the non-religious cause of any disease, Hippocrates allowed future studies and observations to elucidate the concept of blood circulation. Alexandria's school erroneously described the roles of respiration and air transfer up to the viscera. "Arteries are filled with air". Galen demonstrated the absence of air in arteries, but sticked to the opinion of two forms of blood: "spirituous" from the left and "trivial" from the right. The Galenic system implied the presence of anatomic communications between the trivial (right) and spirituous (left) hearts. Genuine Galen's works were lost for the two thirds, but one third was transmitted to the Middle Age and Renaissance by hispano-arabic physicians. Moreover, one of them criticized the Galenic views about transfer of blood from the right to the left via intracardiac holes. The presence of these Galenic cardiac holes could not be visualized by Vesalius, while Servet stressed the crucial role of the lung for the right-left transfer. It was Harvey's achievement to make the synthesis of the real nature of blood continuously circulating from right to left and from left to right via the lungs thanks to the propelling function of the cardiac muscle and without any action of arteries.