This is a novel by Norwegian author Jostein Gaarder.
It sells itself as a juvenile fiction and a history of philosophy. Now this is an amazing book in one aspect only: it is the first book, since I started reading for fun, that I could not finish. This book is horrible. It is painful to read. I found I would rather fill my time sitting, thinking about how much I did not want to open this book, than reading it.
In terms of philosophy, there is a reason this book is in the fiction section and not the reference section; there is a reason this book was first published in Norwegian before being translated into English. If you want names and dates, this book could help, but you'd save a lot of time using wikipedia instead of this book. For a summary of the philosophies, there can be nothing worse than this book. The author is incredibly biased in what is included and what is not. Even within the philosophies included, I spotted numerous instances of half-truths, misleading information, and some simple lies. For example, at one point the author explains how Christians don't believe that humans have souls. This seemed ridiculous enough to me that I had to check just in case everything I had learned for the past 6 years was wrong, so I wrote to a reverend I know with the passage in question quoted. He replied that Gaarder was flat out wrong. I can't emphasize enough, if you want to learn about philosophy, DO NOT READ THIS BOOK!!!
Now, there is a little bit of a story line about a 14 year old girl who secretly meets with a middle-aged man. (Maybe in Norway this is fine?) For the most part this is a boring and pointless attempt to string together long, long, long, long, long, long, long, long, long, longlonglonglonglonglonglonglonglonglonglonglonglonglong.... dialogues about philosophy. In my humble opinion, this plot is superficial, lame, and worthless, but in all fairness, I only read 275 pages before giving up.
So, who should read this novel? No one. It should be avoided at any cost. If someone gives this book to you as a gift, hand it right back. If you happen to come across a pile of these soaking in gasoline in some back alley, do the world a favor and throw a match into the mix. Only an intellectual masochist or a complete idiot would manage to get through this entire book.