In The Citadel of the Autarch, Wolfe's hero indeed comes to the end of his narrative, though neither his life or career…. Severian, as Autarch, sees himself as "an ancient buzzing with antiquity as a corpse with flies," and the description is apt as well for the narrative, in which Wolfe reveals a cyclical theory of time and space, not incompatible with Plato's, and the myth of the New Sun is at last adumbrated.
Wolfe's achievement, though, is nothing less than the mythic conflation of the whole of human drama, something the "first reader" of such a book may sense, but no review can possibly summarize.
Let me say, instead, that the conclusion of Severian's story is both wondrous and intense, and marked by occasional passages of such elegant and evocative prose as to pass into poetry….
I will not comment on the plot further than to say that Severian, as the Autarch himself, unravels most (not all) of the mysteries remaining from earlier books, and that despite a vision of Urth as glaciated waste, presented by a future scientist whose "probability" is "rooted" in Severian's present, the Autarch is convinced that his final mission, to survive a cosmic trial on behalf of humanity, will succeed, and a new sun bloom.
Bob Collins, "Conclusion of 'The Book of the New Sun'," in Fantasy Newsletter (copyright © 1982 by Florida Atlantic University), Vol. 5, No. 11, December, 1982, p. 36.