The distinctive approach of this commentary is that it argues for Solomonic authorship combined with a negative, under the sun approach to the message of the book. These two ideas are related to each other because the book reflects the struggles of Solomon during the period of his life when his heart was turned away from the Lord (1 Kings 11:9).
The purpose of the book is to warn against speculative wisdom which is a wisdom that no longer operates from the right foundation of the fear of the Lord. The struggles of Solomon are laid out as a warning to all that even someone as wise as Solomon can operate on the wrong basis. Of course, the answer to the struggle comes back at the end of the book.