Abstract

THE CONVICTION that nature as ordinarily experienced is the manifestation of a deeper, more extensive physical reality is now commonplace. While Aristotle could believe that the visible qualities and substantial forms of the perceptual world correspond to the real natures of things, the advent of modern classical mechanics, incorporating the atomic theory, dispelled this notion. As in the ancient atomic theories of Leucippus and Democritus, the composition, motion, and qualitative changes of phenomena were attributed to the interaction of "insensible particles," atoms or corpuscles, due to the influence of forces such as gravity, impact, and acceleration. Yet even in the Hellenistic world the search for "hidden causes" to explain observable phenomena was an established tradition, as indicated in this passage from the first century A.D.