Book 26 is the summary book. That means that we can use this book as presenting an outline. For Montesquieu returns to everything previously covered in Spirit of the Laws, creating an outline to show the parts in their totality. If we were reading the book from the beginning to the end, we would find in Book 26 a recapitulating outline of the main arguments. They can be placed alongside the developing argument throughout the book, with the only strong exception a total absence of any discussion of climate or material determinism. That question has been put to rest. We observe as much through the discussion of Book 19, where we may observe that, whatever influence climate might have, the potential for human intervention is stronger in terms of producing political coherence.

Climate, thus, is absent, while everything else is included in the outline of Book 26. That enables us to assess how well the argument has been completed. Following Book 26 comes Book 27, the single-chapter book, in which Montesquieu addresses the question of the character and capability that can formulate legislation in conformity with the principles of the outline. What follows the summary, in other words, is the conclusion concerning how the act of legislation is accomplished.

Now, Book 27 is followed by Book 28, which was originally to be the closing book of the entire work. In that book Montesquieu focused on French history, illustrating the development of the principles of analysis and the susceptibility of France to be influenced by these principles. That was originally to be the conclusion, as we see in Book 18 (to which Montesquieu added a chapter 28 echoing Book 28 and providing an indication of how the several parts are coordinated).

Finally, however, he appended three additional books, 29 through 31, which further elaborated the application to and through French history. Thus, the final books, 28 through 31 focus intently on France itself. We may draw two conclusions from this. First, Montesquieu does due justice to France in light of the extended treatment of England. Apart from the discussion of the Salic Laws in Book 18 (which are not exclusive to France) there is little discussion of France throughout the first 27 books. That makes the close of the work appear almost an afterthought. It may also be Montesquieu's way of projecting reform in France.