Having traced the origins and growth of scientific rationalism from Theogony through Ptolemy in the previous volume, Volume II begins with the fourteenth century critique of Aristotle's mechanics and ends with the development of quantum mechanics. The contributions to the breakdown of Aristotle's cosmology and its replacement with Newton's mechanistic world view are presented, along with subsequent developments in electricity, the emergence of modern chemistry with the overthrow of the phlogiston theory, and the creation of modern atomism. Finally, the evidence for the composite nature of the atom and the probing of its structure by Rutherford are discussed, as well as the revisions of classical mechanics owing to Einstein's relativity theory and the development of quantum mechanics by Planck, Bohr, Heisenberg, Schrödinger, and Dirac.