edgar whitney was perhaps the most influential american watercolor instructor of the 20th century, and this book (first published in the 1960's) is the popular and definitive statement of his painting principles. be warned: this is actually a book on visual design, with emphasis on the "six pattern schemes," the "rule of good form," the seven principles and eight elements of design, and so forth; technical advice is limited to wet in wet and texturing methods, and a fine chapter on drawing, the "foundation of all visual art." whitney's paintings -- which strike me as crass and histrionic -- may warn you about the level that "art" can sink to when it's based on simple formulas. but whitney is inspiring as a teacher, not as an artist, and his teaching is animated by a belief in the high purposes of art, the importance of craft, practice and scholarship, and by a disarming attitude of honesty and earnestness in everything he says. personally, i think the watercolor volume by skip lawrence (a whitney student) provides a better design introduction, but whitney's book is a classic -- fun to read, invaluable to refer to, and it may even improve your painting style.