Did Arthur Conan Doyle say “Mediocrity knows nothing higher than itself, but talent instantly recognizes genius.”?

Did Arthur Conan Doyle say “Mediocrity knows nothing higher than itself, but talent instantly recognizes genius.”?

Found word for word. Yes. The text appears in works attributed to Arthur Conan Doyle. Source and location below.

… n and respect of the Scotchman for his amateur colleague were profound, and he showed them by the frankness with which he consulted Holmes in every difficulty. Mediocrity knows nothing higher than itself; but talent instantly recognizes genius, and MacDonald had talent enough for his profession to enable him to perceive that there was no humiliation in seeking the assistance of one who already stood alone in Europe, both in his gifts and in his experience. Holmes was not prone to friendship, but he was tolerant of the big Scotchman, and smiled at the sight of him.
The Valley of Fear — Sir Arthur Conan Doyle, Chapter 1--The Warning · ¶75 · Public domain (US), Project Gutenberg #3289 · source

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