At the close of this long letter he explains how the literal sense of the passage accords with the Copernican system. By his discovery of the solar spots the revolution of the sun on its axis is demonstrated; moreover it is also very probable that the sun is the chief instrument of nature, the heart of the universe so to speak, and not only, as is known with certainty, is the source of light to the planets revolving round it, but also lends them their motion. If, further, we accept with Copernicus a revolution of the earth, at any rate a diurnal motion on its own axis, it would certainly suffice merely to stop the sun in his course, in order to bring the whole system to a standstill, and thus to prolong the day without disordering nature.[91] Castelli saw nothing ominous in this exhaustive reply to the Grand Duchess Christine’s objections, and took care to give it a wide circulation by means of numerous copies. Galileo’s enemies, however, eagerly grasped the dangerous weapon thus guilelessly placed in their hands by his friend. They ingeniously gave a meaning to the epistle which exactly adapted it to their purpose. They turned Galileo’s emphatic opinion that the Scriptures had no business in a scientific controversy into the reproach that he assailed the universal authority of the Bible; by making Joshua’s miracle the subject of his disquisitions he laid himself open to the cutting remark that the statements of Holy Scripture must be protected from the arbitrary interpretations of profane laymen. Gherardini, the worthy bishop of Fiesole, who was apparently entirely unaware of the existence of Copernicus, was so enraged about the system that Galileo had defended that he publicly insulted him, and threatened to bring the matter before the Grand Duke. He could only be pacified by being informed that the founder of that system was not any man then living in Tuscany, but a German who had died seventy years before, and that his work had been dedicated to Pope Paul III., and had been graciously accepted by him.