  These themes are particularly evident in Planck’s celebrated (1908) Leiden lecture on “The Unity of the Physical Universe”, directed at Ernst Mach’s phenomenalistic Naturphilosophie (Planck 1960, 1–26). Without going into details, Mach regarded physical objects as unnecessary hypostasizations, implying that the mechanical view underlying physics is little more than an elaborate myth. The physics of the matter were effectively settled when Planck secured the mechanical foundations of irreversibility in his Radiation Law of 1900 by relying on Ludwig Boltzmann’s statistical approach to thermodynamics which, in turn, implied atomism. Yet it remained to establish the philosophical implications of these achievements. In his Leiden lecture, Planck argued that this result presented an objective world-picture abstracted from its anthropomorphic origins to produce a synthetically unified image of the world (Planck 1960, 6). Such a view, Planck argued, can only be produced through the unification of the diverse fields of physical phenomena if they are synthesized by means of mathematical abstraction. Such abstraction generalizes the sign-theory to apply to theoretical as well as perceptual representations, resulting in a full-blown structuralist epistemology (Planck 1933, 84ff.; Planck 1949, 105). And it is this method of abstraction that produces the synthetic unity grounding scientific objectivity.  The result is that physical entities are ‘objective’, in the Kantian sense, since they embody the lawfulness of appearances. Indeed, Planck insisted that what is ‘objective’ is precisely what the heroes of the history of science, from Copernicus to Faraday, would have regarded as ‘real’ (Planck 1970, 25–6).  Despite the strident Kantian themes of Planck’s argument, his conclusion has always been regarded as a particularly virulent form of convergent realism (Stölzner 2010).