Many reviewers of EMPIRE OF SILENCE have remarked on the analogies with DUNE so I want to spell out those with BOOK OF THE NEW SUN.
Note: This is in no way to call into question the originality of the book, but to trace out some of its aspects of intertextuality, homage, or what Christopher Ruocchio calls his “evangelism”. Gene Wolfe’s saga itself borrows key elements from LORD OF THE RINGS).
1) The Chantry/the torturers’ guild,
2) Hadrian kills a Sun to win the war/ Severian kills a Sun to bring the New Sun,
3) First person self-justifying unreliable narrator Hadrian/Severian,
4) Bildungsroman of protagonist fleeing a future career as a torturer
5) Highmatter sword gifted to Hadrian/the sword Terminus Est gifted to Severian,
6) Tallness of palatine ruling class/Tallness of exultant ruling class
7) Energy lances
8) Shadow of the executioner/Shadow of the torturer
“The count’s shadow might as well have been that of the executioner” (EMPIRE OF SILENCE page 289)
9) Lictors
10) Hadrian’s ring heavy around his neck/Severian’s Claw heavy around his neck
11) Hadrian’s mission at the end is conciliator/Severian becomes the Conciliator
“Ligeia glanced a moment at Lord Balian, who only shook his head. Her voice now carrying a fraction of its earlier forcefulness, she said, “What, then? Conciliation? Surrender?” “No one is saying anything about surrender, ma’am,” said old Sir William Crossflane from his place beside the tribune” (EMPIRE OF SILENCE, 568).
12) Both books are only approximately translated from a not yet existing future language
13) Apostrophe to the reader at the end. Compare:
“If what I have done disturbs you, Reader, I do not blame you. If you would read no further, I understand. You have the luxury of foresight. You know where this ends. I shall go on alone” (EMPIRE OF SILENCE, 578).
and
“Here I pause. If you wish to walk no farther with me, reader, I cannot blame you. It is no easy road” (THE SHADOW OF THE TORTURER, 210).
14) Meditation on symbols as our masters:
“We think ourselves the masters of such symbols, but they are our masters” (EMPIRE OF SILENCE, 437).
and
“We believe that we invent symbols. The truth is that they invent us; we are their creatures, shaped by their hard, defining edges” (THE SHADOW OF THE TORTURER, 14).
To repeat I must emphasise that I am talking primarily about a matter of parallels and intertextuality, not derivation and originality. Science fiction is a vast mega-text, a meta-game to which many contribute by catching the ball and then passing it on to someone else.