After the dissection of the five Teguments, and the removal of the Muscles, as in the lower Belly, the Anatomist proceeds to lift up the _Sternum_ or Breast-Bone, by separating it from the Ribs; then it is laid upon the Face, or else entirely taken away, to the end that the internal Parts of the Breast may be more clearly discover'd; whereupon immediately appear, the Heart, the Lungs, the Diaphragm, and the _Mediastinum_, which sticks to the _Sternum_ throughout its whole length. _What is the Heart?_ It is a most noble Part, being the Fountain of Life, and the first Original of the Motion of all the others; on which account it is call'd _Primus vivens_, & _ultimum moriens_; that is to say, the first Member that begins to live, and the last that dies. _What Parts are to be consider'd in the Heart?_ Its fleshy Substance, with all its Fibres turn'd round like the Skrews of a Vice; its _Basis_, Point, Auricles, Ventricles, large Vessels, _Pericardium_ and Ligatures or Tyes: The _Basis_ is the uppermost and broadest part; the Point is the lowermost and narrowest part; the two Auricles or small Ears being as it were little Cisterns or Reservers, that pour the Blood by degrees into the Heart, are situated on each side above the Ventricles. The Ventricles, which are likewise two in Number, are certain Cavities in its Right and Left Sides. The large Vessels are the _Aorta_ or great Artery, and the _Vena Cava_ together with the Pulmonary Artery and Vein. The _Pericardium_ is a kind of Bag fill'd with Water, wherein the Heart is kept; which is {79} fasten'd to the _Mediastinum_ by its _Basis_, and to the large Vessels that enter and go out of its Ventricles. _What are the Terms appropriated to the continual beating of the Heart?_ They are _Diastole_ and _Systole_, from whence proceed two several Motions, the first whereof is that of Dilatation, and the other of Contraction, communicated to all the Arteries which have the same Pulse. _To what use serves the Water contain'd in the _Pericardium_?_ It prevents the drying of the Heart by its perpetual Motion. _What are the Lungs?_