In writing this book I have been helped by many UN diplomats and officials. They will recognize their observations and assessments throughout. If the acknowledgments are not more specific, it is only because anonymity is one of the obligations of the diplomatic calling. There are accounts in this book of conversations between Mr. Hammarskjold and various statesmen and diplomats. These were reported to me by second or third parties. Mr. Hammarskjold was a faithful practitioner of quiet diplomacy for whom the rule of discretion was absolute. I had the benefit of several private talks with Mr. Hammarskjold, who agreed to the writing of this book but urged me to keep it as impersonal as possible.