Cryptomnesia (n.) does not explain every idea of unknown origin — innate patterns can produce nearly identical ideas in quite unrelated people.
Cryptomnesia (n.) made a writer omit from his memoir a little lecture Jung had given him — and then reproduce it, significantly, in another book on that very subject.
Cryptomnesia (n.) is a memory that returns without being recognized as memory, tied to the ego by the fewest associations, so it feels like original creation; Nietzsche's Zarathustra unknowingly repeated a ghost tale from Kerner, down to the shooting of rabbits.
Cryptomnesia (n.) is hidden memory, the reappearance of something once read or heard without awareness of its source, as when a woman ignorant of the Bible dreamt a fitting gospel reference.
Cryptomnesia (n.) put into Zarathustra a ship's tale of men flying into Stromboli that Nietzsche had read in Kerner at eleven and retold as his own invention.