  We relate Leibniz homology to cyclic homology by studying a map from a long
exact sequence in the Leibniz theory to the ISB periodicity sequence in the
cyclic theory. This provides a setting by which the two theories can be
compared via the 5-lemma. We then show that the Godbillon-Vey invariant, as
detected by the Leibniz homology of formal vector fields, maps to the
Godbillon-Vey invariant as detected by the cyclic homology of the universal
enveloping algebra of these vector fields.
