During recent decades, our vision of the world of physics - from the subatomic world to the cosmos - has undergone a profound evolution. In this book, one of the scientists who contributed to this development narrates the story of his life and his work. Bruno Rossi gives a close insight into his experiences as a scientist, the motivation which gave direction to his research, and the significance of the results of his experimental work. Rossi was involved at the beginning of very significant stages in relatively recent physics, and recounts how it was at first hand in cosmic rays, high energy physics and space research. He conveys a sense of participation in the excitement of his research, and also an involvement in his life. He writes evocatively of the places where he worked in Italy and America, and gives an insight into the life of a Jewish family living in fascist Italy.