It is human nature to define rules and then push those rules to firmly establish the rigidity of their perimeters.
This book is a compilation of three 1950s publications:
You can get your own copy from Tan Books here.
1. Watch the (live-streaming) Mass from EWTN here.
2. Take a virtual tour of the National Shrine here.
(More virtual tours here.)
The Ten Commandments are rules to follow:
More on the subject of why these versions of the Ten Commandments are different can be found here at Catholic.com.
The main thing to remember is that the commandments are not numbered in the Bible, the catechesis of the church organized the commandments into a list.