a€UKa€’NettleiÅ’DiZ 
Look Into Happiness 
the Science of Smiling

This book discussed the meaning of happiness using the newest psychology and socialism theory. Happiness is divided into three levels: perception, cognition and life. His study indicates that the "adaptation" to happiness is the main reason for unhappiness. The author emphasizes positive psychology which is an important method to adjust people”s understanding of happiness.