HARVEY IN ANCIENT AND
to the other, and re-entering the heart by the vena cava; but he supposed that spirit and blood made their exit from the heart chiefly during wakefulness, while the return was during sleep, and he repeated with strange confusion the old comparison of the move- ments of the blood to the ebb and flow of the tide in Euripus.
Before Harvey there appears to have been some difference of opinion as to whether the heart was muscular, but it was generally believed that the active agent in moving the blood was the act of respiration. Thus, although Harvey found the pulmonary circu- lation ready to his hand, and the term 'circu- lation already attached to it, the course of the blood in the general system was so con- fused with tides and spirits, so destitute of any rational explanation of how the blood which left the heart got back to it, that, as he tells us, he was almost tempted to think, with Frascatorius, that the motion of the heart was only to be comprehended by God. That it was eventually comprehended by Harvey was
