William James, brother of novelist Henry James, was an American philosopher as well as a psychologist. He was the first educator to offer a psychology course in the United States. James was one of the leading thinkers of the late 19th century and is one of the most influential philosophers the United States has ever produced. He has been called the "Father of American psychology".

In this famous essay, James uses his skill as both a philosopher and a psychologist to give a meticulously thought out answer to a question that just about all thinking adults have asked themselves at some point in their lives.