Other online resources on the anatomy and function of the heart are the Latin and English versions of William Harvey's Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus [On the Motion of the Heart and Blood in Animals], in which he famously observed in 1628:
" . . . it is absolutely necessary to conclude that the blood in the animal body is impelled in a circle, and is in a state of ceaseless motion; that this is the act or function which the heart performs by means of its pulse; and that it is the sole and only end of the motion and contraction of the heart." -- Chapter 14, "Conclusion of the Demonstration of Circulation" (translated by Robert Willis).