"Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?"

In this quote, Stephen Hawking is contemplating the concept of an unified theory, which is a single theory that can describe all the basic forces and laws of deep space. He acknowledges that even if such a theory exists, it is just a set of rules and equations. However, he questions what offers these formulas life and meaning, what brings them to life and enables them to explain deep space. Hawking is basically asking what is the driving force behind the laws of the universe and what provides purpose. He is highlighting the mystery and marvel of deep space and the search for understanding its inner functions.