THE AUTHOR'S PREFACE

However, since Galileo had written this in the last years of his life, it was hoped after his death that this dissertation, written by hand, might be found in his private cabinet among other writings, at least not entirely complete. But, not without the sadness of his friends, no page marked with this title was found among his papers, as the heirs of Galileo reported to me. The most famous Torricelli, who, as I hear, tried to search for some traces of this knowledge in his own handwritten lectures on the Infinite Force of Percussion, which I was never allowed to see, testified to the same thing. But no one doubts that Torricelli spoke candidly: he did not demonstrate it, but only collected conjectures by which the infinite force of percussion might be rendered likely and probable. And indeed, with deep silence regarding this matter in Florence both while Torricelli lived and after his death, and because those who attended his lectures always complained that this science had died together with Galileo, it is sufficiently evidenced that Torricelli did not demonstrate the proposition so long desired and arcane.

Therefore, after I saw that I was frustrated in the hope I had conceived, by frequently turning over Galileo's words in my mind, and since I could not be persuaded that that man had been hallucinating, I was brought back many times to the same contemplation: if by chance I could reach the nature of the energy of percussion. But at last, after long agitations of the mind, by the grace of God, I believe that I have discovered this part of physics and mathematics anew by my own effort; and I seem to myself to have clearly demonstrated in this book the true and intimate nature of the energy of percussion, its causes, properties, and effects, which I consider will not be unpleasant, at least on account of their novelty and the excellence of the subject matter. Enjoy these things, reader, while I apply myself to the edition of the remaining books pertaining to the motion of animals. Farewell.