“There’s no feeling like finishing a book, and I’m proud of this one,” Mr. Obama said in a statement. “I’ve spent the last few years reflecting on my presidency, and in ‘A Promised Land’ I’ve tried to provide an honest accounting of my presidential campaign and my time in office: the key events and people who shaped it, my take on what I got right and the mistakes I made, and the political, economic, and cultural forces that my team and I had to confront then — and that as a nation we are grappling with still.”