For the Galvani Bicentenary Celebrations, the University of Bologna and its Academy of Sciences singled out subnuclear physics as the field of scientific research to be associated with this important event, as it would best illustrate, for the new generation of students, the challenge inherent in fundamental sciences. Subnuclear physics was born 50 years ago and has represented, ever since, the new frontiers of Galilean science. In his opening lecture delivered on the first day of the new academic year, Professor Antonino Zichichi analytically reviewed the basic conceptual developments and main discoveries achieved in subnuclear physics during the last 50 years. Given the importance of this field of fundamental research, Professor Zichichi was invited to expand the contents of his lecture into a book, and the outcome is this invaluable volume.