 Direct assault on the problem of satisfying Mach-heavy in a classical framework proved unsuccessful for a long time, despite the efforts of others besides Mach – for example, Friedländer (1896), Föpl (1904), and Reissner (1914, 1915). (Between the late 19th century and the 1970s, there was of course one extremely important attempt to satisfy Mach-heavy: the work of Einstein that led to the General Theory of Relativity. Since Einstein’s efforts took place in a non-classical (Lorentz/Einstein/Minkowski) spacetime setting, we discuss them in the next section.) One very influential approach to implementing Mach-heavy was promulgated in the work of Barbour and Bertotti (1977); this has since developed into the research programme of ‘shape dynamics’, and will be discussed in more detail in section 3 below.