Pick a famous person of the past, and most likely there's a biography about them.
When I finished reading the biography of Alexander Hamilton, I had to stop and think about him. Did I dislike the man because he'd hoped for war so he could further his career, or did I admire him for the meticulous records he kept and his efforts to make the USA financially secure? Days, weeks and now even years later, I'm still thinking about his mistakes, successes and his death caused by a duel.
Taking a person's entire world and condensing it into a book, adding the filter of history, the author's perceptions and then stirring in the viewpoints of others can make it hard for a reader to get a true story of the subject. Reading two biographies of the same person, back-to-back, helps decipher the facts. One book might seem laundered and the other embellished.
When reading The Infernal World of Branwell Bronte by Daphne du Maurier, I was impressed with the book. But I was so appalled by Bronte that I had to get the volume out of my house before I even finished it. The author did such a good job of making Bronte come alive, and did so in such a straightforward manner, that I could feel the pain he caused to others. This is the only book I've ever read that was so good I couldn't finish it.