Includes 13 Covers Inserts (This book comes with a set of 13 cover inserts that represent the 13 categories of artwork presented in the book) Central to the concept of this book is the radical 'mu' for tree, a graphic component of a Chinese character that bears a semantic connection to 'tree'. The usage of this radical is to connote a sense of biophilia in the design. The title of the book is an abstract interpretation of the word 'le', a compound character that contains the 'mu' radical at its base and translates to "happiness" in our context. Radiating from this 'mu' radical, twelve other relevant Chinese characters were chosen from over a thousand characters under the same order. Along with 'le', they were assigned a category in the book's content. The thirteen categories work as thematic boundaries for similarly themed artwork to be nested together.