Diffusion forces and diffusion potentials

Diffusion as classically known is based on Fick\´s law, which describes the rate of flow of the diffusing particles in terms of their density gradient. Recently, a new formulation has been suggested by M.A. Melehy ["A fundamental extension of Einstein??s diffusion-mobility relationship," Nature (to be published)] which is based on forces rather than flow rates. The purpose of this communication is to discuss some simple aspects of the new formulation.