What is an example of omniscient narration in chapter 1 of The Graveyard Book?

In a work of literature, an omniscient point of view is a God's-eye perspective. An omniscient narrator knows all and sees all, giving us a fully rounded picture of the characters and their actions. What's particularly notable about the omniscient point of view is that it can go inside the mind of any character, giving the reader a privileged insight into their thoughts, feelings, and motivations.
A good example of this comes in the opening chapter of The Graveyard Book. As the story begins, we're introduced to a scary man called Jack, who is creeping around a house, preparing to commit several brutal murders. Though to everyone else, Jack may just be nothing more than a common criminal, he regards himself as a professional:




He flexed his fingers. The man Jack was, above all things, a professional, or so he told himself, and he would not allow himself to smile until the job was completed. (Emphasis added.)







Here we see the omniscient point of view in action. It's because the narrator sees all and knows all that the reader is able to discover what Jack tells himself about being a professional.