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.