Martin Eden by Jack London: “Martin was puzzled as to what the discussion was about, but when he rode on to the library he carried with him a new-born interest in Herbert Spencer, and because of the frequency with which the tramp had mentioned "First Principles," Martin drew out that volume.”
The Sea-Wolf by Jack London: “I understood quite a good deal of _First Principles_, but his _Biology_ took the wind out of my sails, and his _Psychology_ left me butting around in the doldrums for many a day.”
The Story of an African Farm by Olive Schreiner: “While I was putting the food on the box he looked at my books; he read their names out aloud. 'Elementary Physiology,' 'First Principles.”
Glimpses of Unfamiliar Japan: Second Series by Lafcadio Hearn: “He has read various epitomes of the history of philosophy in the Occident, and everything of modern philosophy which has been translated into Japanese--including Spencer's First Principles.”
Japan: An Attempt at Interpretation by Lafcadio Hearn: “Assuming, with Herbert Spencer, that the test of reality is permanence, one can scarcely question this position; it differs little from the statement with which the closing chapter of the First Principles concludes:”
Inside My Glass Doors by Natsume Sōseki: “He was bound for the science course from the start, yet he liked to leaf through books of philosophy. I still remember that he once lent me a book called Spencer's First Principles. [auto-translated]”