 The Weltbild tradition influenced the physicists Max Planck and Ernst Mach, who engaged in a heated debate about the precise character of the unified scientific world-picture. Mach’s more influential view was both phenomenological and Darwinian: the unification of knowledge took the form of an analysis of ideas into biologically embodied elementary sensations (neutral monism) and was ultimately a matter of adaptive economy of thought. Planck adopted a realist view that took science to gradually approach complete truth about the world, and fundamentally adopted the thermodynamical principles of energy and entropy (on the Mach-Planck debate see Toulmin 1970). These world-pictures constituted some of the alternatives to a long-standing mechanistic view that, since the rise of mechanistic philosophy with Descartes and Newton, had informed biology as well as most branches of physics. In the background was the perceived conflict between the so-called mechanical and electromagnetic worldviews, which resulted throughout the first two decades of the twentieth century in the work of Albert Einstein (Holton 1998). 