It was in Harvey's lifetime that this stupendous circulation of the heavens "and all that is in them" received its death stroke. Throughout Harvey's years of study at Padua, Galileo had lectured there with great acclaim; and after Harvey's return to London discovery after discovery had followed Galileo's work with the telescope, and had dealt blow after blow to the ancient astronomy. The trial of Galileo had followed; and he had died in 1642, nine years before the publication of Harvey's work On Generation. Yet belief in the ancient astronomy died far harder than belief in the ancient physiology of the movement of the blood. The ancient astronomy was based on the evidence of every man's own eyes, and flattered human vanity with the doctrine that the whole universe was centered upon the globe of which the ordained possessor was the creature made in the image of God. Milton had visited Galileo, famous long before, near Florence in 1638; but in the "Paradise Lost," published in 1667,[447] Milton expressly treated the question between the ancients and the followers of Copernicus as an open one, though Copernicus had died in 1543. Indeed, we find Harvey himself, seven years after Galileo's death, speaking of "the reason why our knowledge of the heavenly bodies is uncertain and conjectural";[448] and saying of opponents of the circulation of the blood: "Nor do they find it satisfactory to set up new systems, as in astronomy, unless these explain all the phenomena."[449] It need not surprise us, therefore, to find Harvey writing as follows in 1628 in the very act of naming his own great discovery:-- "I beg leave to call this motion circular in the same sense in which Aristotle said that air[450] and rain imitate the circular motion of the bodies on high.[451] For the earth, when wet and warmed by the sun, gives off vapor; the vapors are borne upward and condensed and, when condensed into rain, descend again and wet the earth. Thus, too, generation here below and, in like manner, the arising of tempests and meteors result from the circular motion of the sun, his approach and recession."[452] In 1651, nine years after the death of Galileo, in the last words about the moving blood which Harvey published, he drew a parallel between the circulation of the microcosm and the mighty circulation of the macrocosm. This parallel is drawn just before the end of his final work, his treatise On Generation, in a passage of his Exercise On the Innate Heat, in words which may serve to sum up what has gone before. These words shall be quoted without further comment and shall bring our present study of Harvey to an end:--