  Experiment has established that spin-glasses can support a steady-state spin
current $\vec{j}_{i}$. However, the accepted theory of spin glass dynamics
permits oscillations but no steady-state spin current. Onsager's irreversible
thermodynamics implies that the spin current is proportional to the gradient of
a magnetization. We argue, however, that the magnon distribution function
associated with the local equilibrium magnetization $\vec{M}$ cannot diffuse
because it represents $10^{23}$ variables. We therefore invoke the
non-equilibrium magnetization $\vec{m}$, which in spintronics is called the
{\it spin accumulation}. Applying the theory of irreversible thermodynamics we
indeed find that it predicts spin diffusion, and we consider other experimental
consequences of the theory, including a wavelength-dependent coupling between
the reactive and the diffusive degrees of freedom.
