yet to be explored in the English literature. Several aspects of logical positivism, specifically: The first-order theories of Rudolf Carnap's Aufbau (1928, English translation 1967) and of its successor, Goodman (1977), are Leibnizian in their sweep and ambition, although Leibniz would have taken strenuous exception to Carnap's resolute hostility to all metaphysics. The unification of science movement of the 1930s, led by Otto Neurath, Rudolf Carnap, and Charles W. Morris, and later by Edward Haskell et al., bears comparison with the characteristica. Otto Neurath's isotype pictogram system, and "international picture language." The following attempts to recast parts of theoretical science as axiomatic first-order theories can be viewed as attempts to develop parts of the characteristica: Special relativity, by Hans Reichenbach, Rudolf Carnap, and others during the 1920s (Carnap 1958: 197–212); Biology, by Joseph Woodger (1937), also during the 1930s (Carnap 1958: 213–20): Mechanics, by Suppes (1957: 291–305) and others during the 1950s. The objectives of the 'Symbolator' or 'idea-computer' (Goppold 1994) resemble in some respects a less ambitious version of the characteristica universalis. Connections with the Jewish Cabbala, and the International auxiliary language policy of the Baháʼí Faith have also been made. The characteristic has also been claimed as an ancestor of the pictographic Energy Systems Language and associated Emergy Synthesis of Odum's Systems Ecology (Cevolatti and Maud, 2004). The Energy Systems Language combines lines and points with "a kind of pictures" manipulated by means of digital computers and software packages like EXTEND (Odum, Odum, and Peterson 1995), and Valyi's Emergy Simulator. It was designed to provide a general systems language affording quantitative accounting and mathematical simulation of qualitative energy relationships between ecological entities: "that science in which are treated the forms or formulas of things in general, that is, quality in general". A general algebra known as the emergy algebra emerged from the repeated use of this language in modelling and simulating the energetic principles of ecological relations. In particular it afforded the discovery and demonstration of the maximum power principle, suggested as the fourth law of thermodynamics. If this ancestral claim is granted, then simulation software like EXTEND and Valyi's Emergy Simulator can be seen as combining the characteristica and the calculus ratiocinator, if and only if the digital computer is interpreted as a physical embodiment of the calculus ratiocinator. The work of Mario Bunge on the border of physics and metaphysics seems grounded in metaphysical presuppositions similar