I think that I have found a hint as to the right answer in two of
these stories. One is called "The Story of a Book," the other "The
Biography of a Superman." Each is rather an essay than a tale, though
the form of each is narrative. The first relates the sad bewilderment
of a successful novelist who feels that, after all, his great work
was something less than nothing.

He could not help noticing that London had discovered the
secret which made his intellectual life a torment. The
streets were more than a mere assemblage of houses,
London herself was more than a tangled skein of streets,
and overhead heaven was more than a meeting-place of
individual stars. What was this secret that made words
into a book, houses into cities, and restless and
measurable stars into an unchanging and immeasurable
universe?

Then from "The Biography of a Superman" I select this very striking
passage:--

Possessed of an intellect of great analytic and
destructive force, he was almost entirely lacking
in imagination, and he was therefore unable
to raise his work to a plane in which the mutually
combative elements of his nature might have been
reconciled. His light moments of envy, anger, and
vanity passed into the crucible to come forth
unchanged. He lacked the magic wand, and his work
never took wings above his conception.