The reaction of Italian physicists to the innovations of the ‘new physics’ has been studied by analysing their scientific production and their textbooks. Their stand appears to have been the result of several components: absence or weakness of lines of research in the last three decades of the nineteenth century ; firm attachment to the conceptual and philosophical foundations of classical mechanics; and hostility to the quantization of energy. The consequence has been a widening of the gap between the research (...) done in Italy and the main lines of development of the discipline. (shrink)