The method of studying poetry which I have followed in this book was sketched some years ago in my chapter on "Poetry" in Counsel Upon the Reading of Books. My confidence that the genetic method is the natural way of approaching the subject has been shared by many lovers of poetry. I hope, however, that I have not allowed my insistence upon the threefold process of "impression, transforming imagination, and expression" to harden into a set formula. Formulas have a certain dangerous usefulness for critics and teachers, but they are a very small part of one's training in the appreciation of poetry.