In order to make possible a rational utilisation of the means of production, a system of in-kind accounting would have to determine "value" - indicators of some kind for the individual capital goods which could take over the role of the "prices" used in book valuation in modern business accounting. But it is not at all clear how such indicators could be established and in particular, verified; whether, for instance, they should vary from one production unit to the next (on the basis of economic location), or whether they should be uniform for the entire economy, on the basis of "social utility," that is, of (present and future) consumption requirements.... Nothing is gained by assuming that, if only the problem of a non-monetary economy were seriously enough attacked, a suitable accounting method would be discovered or invented. The problem is fundamental to any kind of complete socialisation. We cannot speak of a rational "planned economy" so long as in this decisive respect we have no instrument for elaborating a rational "plan". —Max Weber, 1864 - 1920