# Berthold Gunster ![[2025-08-23_Berthold_Gunster.jpg|400]] Berthold Gunster (born 1959 in Apeldoorn, Netherlands) is a Dutch writer and founder of the Omdenken (Flip Thinking) philosophy. After studying at the Theatre Academy in Utrecht, he worked as a theatre director and writer for years. Since 2001, he and his team have been offering trainings, workshops and shows about Omdenken to companies and individuals. Gunster has written thirteen bestsellers about the Omdenken theory, with his book "Omdenken" standing in the Dutch bestseller list for over 250 weeks. ## Quotes <!-- QueryToSerialize: LIST FROM #type/quote AND [[Berthold Gunster]] WHERE public_note = true SORT file.name ASC --> ## Books <!-- QueryToSerialize: LIST FROM #books AND [[Berthold Gunster]] WHERE public_note = true SORT file.name ASC --> <!-- SerializedQuery: LIST FROM #books AND [[Berthold Gunster]] WHERE public_note = true SORT file.name ASC --> - [[Flip Thinking (book)]] <!-- SerializedQuery END -->