The motivations that brought me to study the early life of Ottaviano Fabrizio Mossotti come from the fact that notwithstanding his scientific importance and outstanding contributions to astronomy, engineering and solid state physics, there is no authoritative, complete or reliable biography about him. Mossotti was highly considered by scientists like Carl Friedrich Gauss, Charles Babbage and William Herschel. Some of the mathematical notation established by him was taken on by Enrico Betti (he made some significant contributions to topology and to other areas of mathematics) who had been his pupil. His ability in theoretical physics and advanced mathematics allowed him to correct the imperfections of some works by Jean and Jacques Bernoulli. Probably his most significant contribution to physics was achieved with a paper published in Turin in 1836 about the foundations of molecular physics. An important piece of mathematical physics, the Mossotti-Clausius formula, concerning the behaviour of the electrostatic dipole, still bears his name. It is therefore quite curious that the study of his life has been neglected so much up to now. One possible reason for this is that although his interest in politics was rather mild, he was known to sympathize with democracy and liberalism, and such views have been condemned by Italian history at least to the end of World War II. Some of the most important histories of science compiled during the fascism decades do not even mention his name.