“These views, as usual, pleased some more, others less; some chid and calumniated me, and laid it to me as a crime that I had dared to depart from the precepts and opinions of all anatomists.... At length, yielding to the requests of my friends, that all might be made participators in my labours, and partly moved by the envy of others, who, receiving my views with uncandid minds and understanding them indifferently, have essayed to traduce me publicly, I have been moved to commit these things to the press.... Finally, if any use or benefit to this department of the republic of letters should accrue from my labours, it will perhaps be allowed that I have not lived idly, and, as the old man in the comedy says:— ‘For never yet hath any one attained To such perfection, but that time, and place, And use, have brought addition to his knowledge; Or made correction, or admonished him, That he was ignorant of much which he Had thought he knew; or led him to reject What he had once esteemed of highest price.’ “So will it, perchance, be found with reference to the heart at this time; or others, at least, starting from hence, the way pointed out to them, advancing under the guidance of a happier genius, may make occasion to proceed more fortunately, and to inquire more accurately.” In the second chapter, after a vivid description of the behaviour of the heart, he thus declares its muscular nature. “The motion of the heart consists in a certain universal tension—both contraction in the line of its fibres, and constriction in every sense. It becomes erect, hard, and of diminished size during its action; the motion is plainly of the same nature as that of the muscles when they contract in the line of their sinews and fibres; for the muscles, when in action, acquire vigour and tenseness, and from soft become hard, prominent, and thickened: in the same manner the heart.”... “These things, therefore, happen together or at the same instant: the tension of the heart, the pulse of its apex, which is felt externally by its striking against the chest, the thickening of its parietes, and the forcible expulsion of the blood it contains by the constriction of its ventricles.” In further chapters he establishes separately, and in a masterly manner, the facts that the pulse in the arteries depends on the contraction of the ventricles; that when the left ventricle ceases to contract, the pulse in the arteries also ceases; that the two auricles contract together, and also the two ventricles together, but the ventricles following the auricles in a certain rhythm; that the heart accomplishes a transfusion of the blood from the veins to the arteries; and that the blood sent into the lungs from the right ventricle passes through the porous structure of the lungs and back to the left ventricle.