This was the first Pilates book I ever bought during my initial training with the Pilates Institute here in Dublin. 

The initial few pages describe the Pilates Principles and basics in an easy understandable way. The book describes various beginners, intermediate and advanced level exercise. You will find variations for most of the exercise, which I find always very helpful. There are lot's of pictures in the book, so you can see how the exercise are done. Still read the text as well, as proper technique is essential. 

I would recommend this book to anybody who want to understand the Pilates basics. It's well laid out and illustrated.