  The classic immanence view is one which identifies material bodies with the combinations of sensations which would appear, in a given situation, if a perceiver were present. Of course, this is just John Stuart Mill’s definition of bodies as ‘permanent possibilities of sensation’ – a treatment which persists in the writings of many of his followers, in one form or another.  For instance, Bertrand Russell, in Our Knowledge of the External World, calls the stable combinations ‘aspects’, declaring that “Things are those series of aspects which obey the laws of physics” (Russell 1922, 110). Specifically, Russell argued that so-called ‘ideal aspects’ – ones which are not presently perceived – may be logically constructed from those which are. Their reality may then be readily assumed. But with this assumption, any grounds of distinguishing between given aspects and assumed ones vanishes, nor is there any means of recovering them, without complicating the system beyond all recognition. Schlick noted that, because of Russell’s sheer audacity in pushing his account to the limit, the result is not prone to the inconsistencies which plague other accounts. Indeed, it is undeniable that Russell’s “bold position” is one of the most successful efforts to carry out the immanence philosophy (Schlick 2009, 502). In a different vein, Joseph Petzoldt acknowledged that esse is not the same as percipi, though he then endeavored to identify the existence of objects with some limited group of sensations, a different group for each perceiver. Despite the countless problems this approach encountered, the critical point which Petzoldt missed is simply that it is impossible to simply identify any particular sensation or group of sensations with a material body, without further conditions relating the sensation or sensations (as, for instance, Russell provided) (Russell 1922, 106). And that is because it is the lawful regularity among sensations which warrants the collection of the series of changing sensations under a single material body. Mach very nearly realized this when, in The Analysis of Sensation, he abandoned Mill’s ‘possibilities’ and replaced them with the mathematical notion of a functional relation. But such a purely mathematical idea can never be substituted for an empirically-based concept of reality. Such efforts are, at bottom, attempts to conceptually embody a law, as epitomized in Helmholtz’ “The Conservation of Force: A Memoir” (Kahl 1977, pp. 49–50).  Specifically, Helmholtz identified the objective power of a law with force, thus reducing the reality of material bodies and scientific entities to a conceptual substitute. But concepts, according to Schlick, can never possess the reality of the contents of consciousness or transcendent things-in-themselves (Schlick 2009, Sec. 25). 