Ever since Thomas Kuhn's influential The Structure of Scientific Revolutions (1962), textbooks have suffered a bad reputation. They have been accused of distorting—at times purportedly—history and of feeding students with an unacceptably simplified and optimistic view of science. This attitude started to change only in recent times. With the increase of attention paid not only to how theories are conceived, but also how they are practiced, disseminated, and appropriated, historians have rehabilitated textbooks as a legitimate site of knowledge production. In (...) this paper, I adopt textbooks as an instrument to unfold multiple facets of the culture that allowed quantum physics to flourish between 1900 and the early 1930s. I organize the article around two stories about two major textbooks, i.e., Sommerfeld′s Atombau und Spektrallinien and Dirac′s Principles of Quantum Mechanics. I explore the complex pedagogical cultures underlying these two masterpieces and how they intersect local agendas. (shrink)