As the saying goes, “There’s no such thing as a new idea.” Whether you’re writing about finance, psychology, real estate, or even yourself, nearly every book written is related to something else that was on the online bookshelf before.

Let’s say that you’re a therapist and you want to write a book about anger. If you log onto Amazon’s Web site and type “anger management,” you’ll find over 5,500 titles. So how would writing a book benefit you?

There are two reasons. First, your book will reflect your one-of-a-kind perspective on the subject. You’ve worked hard to acquire your level of knowledge, and you’ll add to the information that already exists. A book will allow you to share your expertise with others in the most significant way.

Second, from a marketing perspective, your audience doesn’t care how many books have been written on your subject. Again, let’s take the example of the therapist writing a book about anger. When a prospect calls, and the therapist tells him that she has published a book on anger, she’s gained unparalleled credibility.

Furthermore, newspapers, magazines, web sites, radio, and TV are always looking for an interesting story to cover and expert advice. Whom do they usually consult? A published author.

Your book will work hard for you. It will help you reach your goals faster, and unlike newsletters that get read (we hope) and tossed in the recycle bin, people keep books. It’s the world’s most impressive business card.