This agile small "book" (in Italian) is an introduction to the life and work of Ettore Majorana, the brightest Italian theoretical physicist of the XX century, regarded by Enrico Fermi as the best theoretician of his time in the world. It consists of ten smooth chapters, only few of them being moderately technical, and of three Appendices: (i) about his inaugural lecture on physics at the University of Naples; (ii) about some notes of his, on the role of the statistical laws in physics and in the social sciences; and (iii) with a recapitulatory biographic outline. The present material is mainly taken from our previous book "Il Caso Majorana: Epistolario, Documenti, Testimonianze", first published (1987, 1991) by Mondadori, Milan, and recently (2000, 2002, 2008) published by Di Renzo Editore, Rome. That book presented practically all the serious documents existing on Majorana's life & work [indeed, almost all the biographical documents have been discovered or collected, during a few decades, by the present author, who was the first to publish them]. Actually, we might address to such a book (c/o www.direnzo.it, "Arcobaleno" series) all the readers interested in more and deeper information., Comment: An agile short "book" of 56 pages, in Italian, consisting in 10 smooth chapters and 3 Appendices. In pdf (the original source-file being in Word)- Replaced eliminating a defect (and better specifying the existing copyright)