"How to Win Friends and Influence People" is just as useful today as it was when it was first published, because Dale Carnegie had an understanding of human nature that will never be outdated. This book is all about building relationships. Financial success, Carnegie believed, is due 15 percent to professional knowledge and 85 percent to "the ability to express ideas, to assume leadership, and to arouse enthusiasm among people." He teaches these skills through underlying principles of dealing with people so that they feel important and appreciated. He also emphasizes fundamental techniques for dealing with people without making them feel manipulated.