  We derive a unified theory of spin and charge degrees of freedom in a
ferromagnet. The spin-transfer torque and spin electromotive force are examined
from the coarse-grained perspective of collective coordinates. The resulting
equations of motion reflect a balance of conservative, gyroscopic
(Berry-phase), and dissipative forces. We then expand the space of collective
coordinates by adding the electric charge. The adiabatic spin-transfer torque
and spin emf turn out to be a gyroscopic force; their nonadiabatic counterparts
are a dissipative force.
