Institute and Museum of History of Science, Florence, ITALY

 Evangelista Torricelli

2. With Galileo in Arcetri

Letter from Benedetto Castelli to Galileo Galilei of 2 Marzo 1641. It is published in Opere diGalileo Galilei, Edizione Nazionale, Vol. XVIII, p. 803.

We know little about the activities of the young Torricelli in the years between 1632 and 1641. It has been ascertained that he followed Mons. Giovanni Ciampoli to the Marche, where the noted prelate had been sent as a governor after the condemnation of Galileo. Ciampoli was ready to distance himself from Rome for the sake of the friendship and admiration he had always felt for the author of the Dialogue. During this lengthy period, Torricelli investigated the theory of motion, as is revealed by a letter from Castelli to Galileo of 2 March 1641. The Abbot had been authorized to visit Galileo, a prisoner in his Villa at Arcetri. Sending the good news to his Master, he promises to "bring him a book, and perhaps even the second book, written by a disciple of mine [...] who has demonstrated many of those propositions De Motu which Your Lordship had already demonstrated, but differently, constructing marvellously on the same material [...]". The "disciple" was none other than Evangelista Torricelli, who had returned to Rome at the beginning of 1641. The book was favourably received by Galileo, and Castelli, shocked by the blindness and the ailments afflicting his illustrious host, feared that his most recent "speculations" might be lost, and proposed to send Torricelli to Florence to aid him in the composition. [See the description by Vincenzo Viviani, communicated by Ludovico Serenai, in Torricelli, Opere, edited by G. Loria and G. Vassura, Faenza, 1919, vol. I (1), p. VI].
Castelli's proposal was accepted by Galileo immediately, and, two weeks later, on 27 April 1641, Torricelli wrote to the prisoner in Arcetri to thank him for the invitation and express his regret that he was unable to leave Rome until the abbot's return. Castelli's absence was prolonged until Autumn, and it might be wondered whether this was the only reason for Torricelli's reluctance to depart. It is clear that a good deal of courage was required, in the political and cultural context of the period, to go to gather the ideas of one whom the all-powerful inquisitors of the Holy Office wanted to silence permanently. And Torricelli, although he continues to write to Galileo, gives no precise inducation of the date of his arrival. He seems rather to hesitate on the decision of whether he should move to Florence. Galileo expressed his regret on this point in a letter of 27 September 1641. After having thanked Torricelli for having sent him his work on spirals, he continues thus: "[...] it seems to me that one or two sheets of paper would not be sufficient to give you the praises you deserve, however I was looking forward to paying this duty and debt to to you in person, living in the hope that I might have this pleasure for some days before my life, already close to the end, should be over. In a most loving letter of yours, Your Lordship gave me no small hope that this desire of mine might be fulfilled, but I detect no hint of confirmation in your last letter. Rather, from what I understand from your other letter written to the most Reverend Father Castelli and sent to me opened, I have very little or nothing left alive in this hope of mine. I don't want to have to try to hold back those good encounters and events that must justly happen to one of your valour, so far elevated above the common sciences. But I will tell you with sincere affection that the merit of your peregrine mind might also be recognised here, and my low hovel might not be a less comfortable abode for you than some of the most sumptuous, because I am sure that you will not find the affection of the host more fervent in any other place than in my breast; and I know well that to true virtue this is more pleasing than any other comfort".
Galileo's words had an almost instantaneous effect. During the first days of October, Torricelli left for Florence. There, under the guidance of his venerable master, he wrote out the Fifth day, to be added to the other four of Galileo's Discourses and mathematical demonstrations concerning two new sciences, already published in Leiden by Elzevir in 1638.
The death of Galileo on 6 January 1642 brusquely interrupted the work of Torricelli, who decided to return to Rome immediately. He was about to leave when Ferdinando II dei Medici proposed that he should remain in Florence with the title of "mathematician of the Grand Duke of Tuscany" and "Reader in Mathematics" in the university of Pisa. This nomination, accepted immediately marked the beginning of an intense period of activity for Torricelli, in the course of which he elaborated the solutions to numerous problems in mathematics and physics.


Galileo Galilei

Evangelista Torricelli

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