Various attempts have been made to account for the complete failure of Greek physical science by assigning this and that specific tendency to the Greek mind: but it seems a perfect confirmation of the view I have here presented--to wit that the organic error was not Greek but simply a part of the general human lack of personality--to reflect that 1,500 years after Aristotle, things are little better, and that when we do come to a time when physical science begins to be pursued upon progressive principles, we find it to be also a time when all other departments of activity begin to be similarly pursued, so that we are obliged to recognize not the correction of any specific error in Greek ratiocination, but a general advance of the spirit of man along the whole line. And perhaps we have now sufficiently prepared ourselves, as was proposed at the outset of this sketch of Greek science, to measure precisely the height of the new plane which begins with Copernicus, Kepler and Galileo in the 16th century, over the old plane which ended with Aristotle and his commentators. Perhaps the true point up to which we should lay our line in making this measurement is not to be found until we pass nearly through the 17th century and arrive fairly at Sir Isaac Newton. For while each one of the great men who preceded him had made his contribution weighty enough, as such, yet each brings with him some old darkness out of the antique period. When we come to examine Copernicus, we find that though the root of the matter is there, a palpable environment of the old cycle and epicycle still hampers it; Galileo disappoints us at various emergencies. Kepler puts forth his sublime laws amid a cluster of startling absurdities; Francis Bacon is on the whole unfaithful; Descartes will have his vortices or eddies as the true principles of motion of the heavenly bodies; and so it is not until we reach Sir Isaac Newton at the end of the 17th century that we find a large, quiet, wholesome thinker, de-Aristotleized, de-Ptolemized, de-Cartesianized, pacing forth upon the domain of reason as if it were his own orchard, and seating himself in the centre of the universe as if it were his own easy chair, observing the fact and inferring the law as if with a personal passion for truth and a personal religion towards order. In short, and in terms of our present theory, with Sir Isaac Newton the growth of man's personality has reached a point when it has developed a true personal relation between man and nature.