That's a question of a lifetime because as you change, mature, books "change" as well every time you read them. With that said, many people approach this by choosing the author(s) first or the historical period, and then drilling down to specific titles. Parent mentioned some authors that were relevant to him/her. Don Quixote (book title) is a great book and it had a special meaning to me when I read it for the first time. It was when I was learning Spanish and consulting in Latin America. Quixote is well regarded as a literature masterpiece for the Spanish language and, to me, as a learner, it was like playing the piano while listening to Beethoven as a reference. Well, this was my own experience. You can choose authors/books to build your own experience around them, which I'm sure you will never forget.
