then passed through the veins and along the vena cava and so round to the left ventricle in the manner already indicated. This movement we may be allowed to call circular." Harvey's great discovery is here formulated in his own words. The lesser or pulmonary circulation was already tolerably well known, owing to the work of Realdus Columbus, the successor of Vesalius in the anatomical chair at Padua, though he had been anticipated by Servetus, who published it at Lyons in 1543 in the "Christianismi Restitutio," a theological work, containing doctrines for which Calvin caused him to be burnt. But it is more than doubtful whether Harvey knew of this work, as not more than three or four copies of it have escaped the flames which consumed the book and its writer. Harvey continues his treatise by laying down three propositions to confirm his main point that the blood circulates. First, that the blood is incessantly transmitted by the action of the heart from the vena cava to the arteries. Secondly, that the blood under the influence of the arterial pulse enters and is impelled in a continuous, equable, and incessant stream through every part and member of the body, in much larger quantity than is sufficient for nutrition or than the whole mass of fluids could supply. Thirdly, that the veins return this blood incessantly to the heart. "These points being proved, I conceive it will be manifest that the blood circulates, revolves, is propelled, and then returning from the heart to the extremities, from the extremities to the heart, and thus that it performs a kind of circular movement."