 The Atomlehre was Fechner’s contribution to a major controversy in the mid nineteenth century: the existence of the atom. Fechner argued that, by the best standards of observation and experiment then current in physics, the most probable view is that atoms really do exist; they are not only a convenient fiction or a fallacious hypostasis. The simplest and most consistent interpretation of the data of observation and experiment is that there are atoms behind the laws of experience. 