  We develop the simplest possible theory that gives reason of the recent
experimental observations that two heavy spheres, immersed into a mono-layer
bath of poppy seeds, attract one another when shaken harmonically in a single
horizontal direction. Their attraction is so strong that the two spheres remain
bound during hundreds of driving periods. The paper consists of three
independently readable Chapters, with only a few inter-chapter references. The
first Chapter concerns itself with the the motion of a roller amidst a
horizontally shaken sea of poppy seeds, under the Assumption of equal phase for
rotational and translation velocities. The second Chapter details how this
predicts the observed longitudinal diffusion of a single sphere in a bath of
poppy seeds. The third Chapter shows how to retrieve all relevant physical
parameters from experiment: viscosity of the seed bath, friction of the heavy
spheres with the harmonically moving substrate, equilibrium rates for
dissociation of bound pairs or binding of lone pairs, and the full Gibbs
potential surface as a function of experimentally accessible parameters.
