An index is an investment:  

• An index adds value to a book; it becomes a research tool which is useful to readers.  
  
• An index will make a book accessible:  it anticipates the needs of readers, ensuring that they will find what they are looking for and it will enable them to explore other themes.  
  
• At a glance an index allows for a brief overview of the content to encourage readers to buy the book.
  
• A professionally prepared index will enhance the use and value of a book.