The Ways of the Righteous and of the Ungodly

Psalm one is the prelude to the rest of the book. If you pick up most any book you find there is an introduction and/or a preface to the book. It is important to read these beginning pages, because there the author is providing the reader with an overview of what is to come in the subsequent chapters. For novels, it may be the backstory needed for some of the main characters and for other books such as thematic, doctrinal, or, theological books, the preface is preparing the reader for the matters to be discussed.

Think of it this way, as the foundation is to a building, Psalm chapter 1 is to the whole book.