During this last period of his life also, he again took up the negotiations with the States-General, broken off by his severe illness in 1638. After he became blind he had given up all his writings, calculations, and astronomical tables relating to the Medicean stars, to his old pupil, Father Vincenzo Renieri, in order that he might carry them further; he was well adapted for the task, and executed it with equal skill and zeal.[577] The new ephemerides were just about to be sent to Hortensius, when Diodati informed Galileo of his sudden death in a letter of 28th October, 1639.[578] The three other commissioners charged by the States-General with the investigation of Galileo’s proposal having also died one after another, in quick succession, it was difficult to resume the negotiations. The interest of the Netherlanders in Galileo’s scheme (perhaps from its acknowledged imperfection) had also evidently cooled, and his proposal to replace the commissioners was not carried out, although he offered to send Renieri to Holland to give all needful explanations by word of mouth. Galileo’s death then put an end to these fruitless negotiations.[579] At the beginning of 1640 Fortunio Liceti, a former pupil of Galileo’s, published a book on the phosphorescent Bolognian stone. In the fiftieth chapter of this work he treats of the faint light of the side of the moon not directly illuminated by the sun, and rejects the view advocated by Galileo in his “Sidereus Nuntius,” that it arises from a reflection of the sun’s rays striking our earth, which the earth reflects to our satellite, who again reflects them to us. Galileo was undecided whether it were not best to take no notice of Liceti’s objections, the scientific value of which he did not estimate very highly, when a letter from Prince Leopold de’ Medici, brother of the reigning Grand Duke, relieved him of his doubts.[580] This prince, who has gained a permanent name in the history of science by founding the celebrated “Accadémia del Cimento,” invited Galileo to give him his views on Liceti’s objections.[581] This challenge sufficed to rouse all the blind old man’s dialectic skill, though he was then seventy-six and bowed down by mental and bodily sufferings. He dictated a reply, in the form of a letter to Prince Leopold, which occupies fifty large pages in the extant edition of his “Opere,” and in fire, spirit, mastery of language, and crushing argument, it is quite a match for the most famous controversial works of his manhood.[582]