Plagiarism is such a broad concept, it it sometimes difficult to tell whether you are citing your sources correctly or what exactly you must cite from the readings. Martin Luther King Jr. was accused of cheating in Chapter 1 of My Word. People were questioning whether to give him the credit he is receiving for his work because he was accused of some plagiarism. I believe although he took some words for other people, he still is the one who made the biggest difference by living the words, not just speaking them.
I am looking forward to reading this book, because I am sure at one point in time I have unintentionally plagiarized someone else's work. Never intentionally, but still, intentional or not it still has the same effect to the person you are taking the words from.