This first attempt of Galileo’s, however, to gain a footing at the court of Tuscany seems to have been unsuccessful. At any rate in the extant correspondence of this period there is not a word more on the subject; and a few months later, after the construction of the telescope, he thankfully accepted the chair of mathematics at Padua offered to him for life by the republic. But this invention and the consequent discoveries had meanwhile acquired such vast importance, and had, as we have seen, raised such a storm in the whole educated world, that it now appeared very desirable to the court of Tuscany to attach to itself for ever the man on whom the eyes of scientific Europe were fixed.
The first steps towards this end were taken when Galileo went to Florence in the Easter recess of 1610 to show his telescopic discoveries to Cosmo II., especially the stars which bore the name of the reigning house. We afterwards find Galileo entering eagerly into the negotiations which followed. In the letter to Vinta before mentioned, of May 7th, 1610, he presses for a decision, for, he says, observing that day after day goes by, he was determined to set a definite purpose before him in the ordering of the life that may be left to him, and to devote all his powers to perfect the fruits of his previous efforts and studies, from which he might look for some fame. He then mentions the conditions on which he at present serves the republic, perhaps in order that they might be guided by it at Florence; but what he lays most stress on is that it is of the utmost moment to him that leisure should be assured him for the completion of his labours, by his being freed from the obligation to give public lectures; but it will always confer on him the highest honour to give lectures to his sovereign, to whom also he will dedicate all his writings.
The same letter is also of the highest interest as giving us an insight into the scientific projects he was then cherishing. He communicates to the Tuscan secretary of state the works the completion of which lies so near his heart. He says:—
“The works which I have to finish are chiefly two books de systemate, seu constitutione universi, a vast project full of philosophy, astronomy, and geometry; three books de motu locali, an entirely new science, for no other inquirer, ancient or modern, has discovered any of the wonderful phenomena which I show to be present in natural and induced motion; I may therefore with perfect justice call it a new science discovered by me from its first principles; three books on mechanics, two relating to the demonstration of the principles and fundamental propositions, one containing the problems; although others have treated of the same subject, what has been hitherto written upon it is neither as to extent nor in other respects a fourth part of what I am writing. I have also various smaller works in view on matters connected with nature, such as de sono et voce, de visu et coloribus, de maris æstu, de compositione continui, de animalium motibus, and others. I am also thinking of writing some books for the soldier, not only to cultivate his mind, but to teach him by select instruction all those things connected with mathematics which it would be an advantage to him to know, as, for instance, castrametation, military tactics, fortification, sieges, surveying, estimate of distances, artillery, the use of various instruments, etc.”[59]
We regard with astonishment the wonderful versatility which we find displayed in Galileo’s works. And amongst them are not only all the larger ones announced in the above letter; his important telescopic discoveries and his ceaselessly active mind led him far to surpass the bounds he had set himself, for he was the first to infuse conscious life into the slumbering idea of the Copernican system.
This memorable letter of Galileo’s soon brought the court of Tuscany to a decision. Fourteen days later, 22nd May, Vinta wrote to him, as a preliminary, that the Grand Duke seemed well disposed to recall him to his native country and to grant all his wishes.[60] He promised to inform Galileo as soon as it was all settled. On 5th June he wrote that Cosmo II. was willing to nominate him as first philosopher and mathematician of the University of Pisa, with an annual stipend of 1000 Florentine scudi, without any obligation to live at Pisa or to give lectures. Vinta requested Galileo to let him know whether he agreed to these conditions, in order that he might have the necessary application drawn up in Galileo’s name, as well as the decree and rescript; the time of their publication shall be left to Galileo, and meanwhile all shall be kept secret.[61] Galileo wished particularly that nothing should be known at Venice of these negotiations, which did not place his gratitude to the republic which had shown him so much favour in the best light, until all was decided and therefore irrevocable.
Having declared himself entirely satisfied with the proposed conditions, in a letter to the secretary of state, the only alteration being that he should like not only to be first mathematician at Pisa, but also first mathematician and philosopher to the Grand Duke himself,[62] the decree summoning him to the court of Tuscany in this twofold capacity was issued on 12th July, 1610.
Notwithstanding all the great advantages which this new post secured to him, it was a very bad exchange for Galileo from the free republican soil to the doubtful protection of a princely house which, although very well disposed towards him, could never offer so decided an opposition to the Roman curia as the republic of Venice. It was indeed the first step which precipitated Galileo’s fate.[63] In the Venetian republic full liberty of doctrine was really enjoyed, in religious Tuscany it was only nominal. In Venice politics and science were secure from Jesuitical intrigues; for when Pope Paul V. thought proper to place the contumacious republic under an interdict in April, 1606, the Jesuit fathers had been compelled to quit the soil of Venice “for ever.”[64] In Tuscany, on the contrary, where they felt quite at home, their influence weighed heavily on everything affecting their own interests, and especially therefore on politics and science. Had Galileo never left the pure, wholesome air of the free city for the stifling Romish atmosphere of a court, he would have escaped the subsequent persecutions of Rome; for the republic which, not long before, had been undaunted by the papal excommunication of their doge and senate, would assuredly never have given up one of its university professors to the vengeance of the Inquisition.
At the beginning of September, 1610, Galileo, to the no small displeasure of the Paduans, left their university, at which eighteen years before he had found willing reception and support when his longer tarriance at Pisa had become impossible; deserted his noble friends, Fra Paolo Sarpi, Francesco Sagredo, and others; and proceeded to the capital of the court of Tuscany on the lovely banks of the Arno, where at first, it is true, much honour was done him, but where afterwards envy, jealousy, narrowness, ill will, and fanaticism combined together to his destruction. One of his most devoted friends, Francesco Sagredo, foresaw it. When Galileo left Venice he was in the East, in the service of the republic, and did not return till the spring of 1611, when he wrote a remarkable letter to his friend at Florence. After having heartily expressed his regret at not finding Galileo on his return home, he states his doubts about the step his friend had taken. He asks, among other things, “where will he find the same liberty as in the Venetian territory? And notwithstanding all the generous qualities of the young ruler, which permitted the hope that Galileo’s merits will be justly valued, who can promise with any confidence that, if not ruined, he may not be persecuted and disquieted on the surging billows of court life, by the raging storms of envy?” It is evident from another passage in the letter that Galileo’s behaviour had made a bad impression at Venice, where they had not long before raised his salary to a thousand florins, and conferred his professorship on him for life; towards the end of the letter Sagredo lets fall the ominous words that he “was convinced that as Galileo could not regain what he had lost, he would take good care to hold fast what he had gained.”[65]
Only a month after Galileo’s arrival at Florence he made a fresh discovery in astronomy which eventually contributed to confirm the Copernican theory, namely, the varying crescent form of the planet Venus. With this the important objection to the new system seemed to be removed, that Venus and Mercury did not exhibit the same phases of light as the moon, which must be the case if the earth moved, for they would vary with her position in the universe. Galileo communicated this appearance, which entailed conclusions so important, and which he therefore wished to investigate more thoroughly before making it known, to his friend and correspondent Julian de’ Medici at Prague, in an alphabetical enigma, as in the case of the singular appearance of Saturn. It was as follows: