 Atomism had become such a controversial issue in the mid nineteenth century partly because of the rise of materialism, and partly because of the traditional reputation of atomism. Materialism had become a rising force in German philosophy in the early 1850s; and by 1855—the very year Fechner published his work—Karl Vogt, Heinrich Czolbe, and Ludwig Büchner published their manifestos of materialism (Vogt 1855; Büchner 1855; Czolbe 1855). The German materialists were not unqualified champions of atomism. Though Czolbe had explicitly defended it (1855: 105 and 1875: 95), Büchner was more cautious, stating only that the atom was still a working hypothesis (1855 [1904: 39–40]). Nevertheless, the reputation of atomism as a materialist doctrine had been formed since antiquity. Atomism, whose chief exposition was Lucretius’ De rerum naturae, stood for a completely naturalistic worldview.