Even though in this book I am interested mainly in the physical conceptions of Maxwell and his contemporaries, I nonetheless must add a few chapters on light theories and related subjects to describe the large framework of meaning in which Maxwell and his contemporaries as scientists worked. I shall take the relevant information again from histories of physics and limit myself again to a bare minimum in so doing. I shall here not make a great effort to explain the interpretive character of the relevant theories and paradigms, even though in the following ages they have become for many scientists "privileged texts," which generated influential "text traditions" as we shall see.