  We show how allowing non-local terms in the field equations of symmetric
tensors uncovers a neat geometry that naturally generalizes the Maxwell and
Einstein cases. The end results can be related to multiple traces of the
generalized Riemann curvatures R_{alpha_1 ... alpha_s; beta_1 > ... beta_s}
introduced by de Wit and Freedman, divided by suitable powers of the
D'Alembertian operator \Box. The conventional local equations can be recovered
by a partial gauge fixing involving the trace of the gauge parameters
Lambda_{alpha_1 ... alpha_{s-1}}, absent in the Fronsdal formulation. The same
geometry underlies the fermionic equations, that, for all spins s+(1/2), can be
linked via the operator (not hskip 1pt pr)/(\Box) to those of the spin-s
bosons.
