  In this paper, we describe a general theory of modules over an algebra over
an operad. We also study functors between categories of modules. Specializing
to the operad E_d of little d-dimensional disks, we show that each
(d-1)-manifold gives rise to a theory of modules over E_d-algebras and each
bordism gives rise to a functor from the category defined by its incoming
boundary to the category defined by its outgoing boundary. We describe how to
assemble these categories into a map from a certain operad to the operad of
(infinity)-categories.
