The main theme could be about Henry's journey within the so - called 'Great Society'. Maybe it's about his personal growth, his relationships, or his experiences in a society that has certain ideals and structures.
The main theme could potentially be the exploration of the concept of the Great Society through Henry's eyes. It might look at how Henry interacts with the different elements of this society, such as its institutions, its people, and its values. It could show his attempts to find his place in it, adapt to it, or even change it in some ways.