On page 261-262 Alberto raises the issue of "rationalism" (in the 17th Century Descartes believed reason is the essential source of knowledge and that man has "certain innate" ideas in his mind prior to any experience). Alberto, as part of the novel's didactic (teaching) theme, then contrasts Descartes' rationalism with 18th Century philosophers including Locke, Hume, and Berkeley who were "empiricists." The empiricist (including the original empiricist thinker Aristotle) believed that "all knowledge of the world" is derived from what our senses tell us. Englishman John Locke, Alberto explains (263), believed that prior to any experience, the human mind is "bare and empty as a blackboard before the teacher arrives." But when we begin having experiences, the truth comes clear because now we have knowledge of those experiences, and the blackboard begins to have writing on it, and knowledge conveyed through it, Locke believed. "Each society has its regime of truth," Foucault wrote (1980, p. 131); and clearly many of the 18th Century leading philosophers believed in the empiricist approach to knowledge, so this type of thinking became "the truth" in that window...

All the philosophers are men, she said on pages 268-269, and they talk about a "world of their own" - a world of ideas. But what about real life? Sophie learned through Hume's ideas that our "impression" (immediate sensation of "external reality) of being burned is stronger than our later realization of that incident (an "idea"). What the mind stores for future reference is the impressions which becomes the "truth...a thing of this world" as Foucault wrote. Why is the act of being burned more apt to remain as the mind's "true" remembrance than the "idea" formed later that indeed I got too close to the stove and it is hot? Because the original sensation - the "impression" of being burned - is real, is true, and is actual, by Foucault's theory, and the later contemplation of that impression is, as Alberto paraphrases Hume on page 269, "only a pale imitation." Hence, knowledge, power, and truth are fully embraced in Gaarder's book through the weaving of characters through time and their interaction with the philosophies that all claimed at one time to be the truth.
Works Cited

Foucault, Michel. (1980). Power / Knowledge: Selected Interviews and Other Writings, 1972-

1977. New York: Pantheon Books.

Gaarder, Jostein. (1991). Sophie's World. New York: Berkeley Books.