Christoph Lüthy

This article opens with a distinction between David Hockney's strong and weak theses. According to the strong thesis, in the period 1430-1860, optical tools were used in the production of paintings; according to the weak thesis, mirrors and lenses merely inspired their naturalistic look. It will be argued that while for the fifteenth and sixteenth centuries, there is little evidence in favor of the strong thesis, the case is different for the seventeenth century, for which the use of optical instruments by painters is a documented fact. In this article, an early case is examined. The extant preparatory drawings of Gaspare Vanvitelli suggest that this cityscape painter relied on a camera obscura. But even here, the strong thesis must be tempered. The fact that several stages of artistic transformation separate the camera obscura projection from the finished painting undermines Hockney's analogy between optically assisted painting and 'naturalistic' photography

Daniel Sennert is one of the more neglected big figures of that seventeenth-century process that goes by the shorthand name of Scientific Revolution. Born in Breslau/wroclaw in 1572, he was professor of medicine at the University of Wittenberg from 1602 until his death in 1637. However, his fame and importance were not due to his classroom teaching but to his writings, which were reprinted throughout the century in Germany, France, England, Italy, and the Netherlands, and partially translated into English. His reputation among both his contemporaries and today’s historians of science has to do with the highly innovative synthesis of natural philosophy, medicine, and chymistry, which he presented notably in the two editions of his De chymicorum cum Aristotelicis et Galenicis consensu ac dissensu and in his late Hypomnemata physica, both of which relied on a novel type of atomistic matter theory. His influence, generally underestimated in today’s scholarship, was felt throughout the century and, as William R. Newman has demonstrated, is particularly important in the case of Robert Boyle, who was “plundering Sennert’s œuvre for proofs of the corpuscularian hypothesis,” albeit without acknowledging his source.

There are many good reasons for seeing Aristotelian hylemorphism and atomism as diametrically opposed theories of matter. Aristotle himself had forcefully combatted the physical model of Leucippus and Democritus, whose ontology consisted of indivisible material bodies moving in an immaterial void, presenting his own model as an alternative. This alternative excluded both indivisibles and the void and postulated instead a plenist world made up of substances all of which were infinitely divisible continua composed of universal matter and specific substantial forms. Unlike elementary atoms, Aristotle’s elementary substances could transmute into one another: water, when evaporating, was said to turn into air.