  Maxwell's original discussions emphasised that the demon needed to have powers of perception and handling the individual molecules far greater than our own. This makes its operation simply a matter of scale and the statistical nature of the second law not probabilistic, but due to our inability to discriminate the exact state of a large number of particles (similar to our inability to exploit Loschmidt's reversibility objection). This leaves open the possibility of a device which could discriminate fluctuations in individual atomic velocities and it is not clear that any probabilistic argument would prevent work being extracted from this. The explanation of Brownian motion by Einstein in 1905, as the effect of statistical mechanical fluctuations, made them appear directly observable and open to exploitation. Earman and Norton (1998) includes a historical review of early attempts to design such devices.