here. The works cited comprise:
an alternative universe fantasy novel;
a historical fiction tetralogy with elements of fantasy;
two future history series;
two time travel novels;
a time travel series;
one volume of an alternative history trilogy, albeit by another author and mentioned parenthetically.
One emergent theme was "chaos," beginning in mythology when Chaos was personified as a Goddess and ending in science fiction when "chaos" is an impersonal principle of quantum mechanics. On every level, human beings strive to defend order and life against chaos and eventual death, the Norse Ragnarok, Dominic Flandry's Long Night.
Poul Anderson's fiction is a worthy conceptual sequel to the Sagas, the Eddas and any other literature that addresses this basic struggle. Hamlet asked, "To be or not to be?" We had no choice about coming into being but can give a good account of ourselves now that we are here.
"Chaos" is ambiguous. It can also signify the unpredictability of complete freedom that Anderson champions against the deadening order imposed by bureaucrats and dictators.