its temple of the goddess of nature, Venus Erycina, said to have been built by Daedalus. As philosophers and historians of the natural sciences, we hope that the stimulating atmo­ sphere of Erice will to some extent be transmitted by these pages. We are especially grateful to that generous and humane physician and historian of science, Dr. Vincenzo Cappelletti, himself a creative scientist, for his collaboration in bringing this work to completion. We admire his intelligent devotion to fostering creative interaction between scientists and historians of science as Director of the School of History of Science within the great Ettore Majorana Centre for Scientific Culture at Erice, as well as for his imaginative leadership of the Istituto della Encic10pedia Italiana.