"When I wrote the first edition of this book, I hoped, of course, that it would be a popular, widely read book. But I didn’t know if people would respond to it or not. It’s been a surprise and a heart warming experience to have the reaction to the book be so positive. The first edition has been translated into several languages and used as a textbook in many universities, and people often show me their well-used book with marks and sticky notes and highlights.

It’s been several years since I wrote the first edition, and most of the material has stood the test of time. There is some new research, however, so I decided it was time to do a second edition. I’ve done updates, and tweaked explanations, wordings, and images, to make sure the book stays current.

A big thank-you to all my readers for your support."

Susan Weinschenk, Ph.D.

Edgar, WI

June 2020