Final answer:
Van Houten's letter, shared by Augustus with Hazel, discusses themes of melancholy, hope for reunion, and the endurance of love, mirroring their personal journey and evoking classic literary expressions of deep emotional experiences.
Step-by-step explanation:
The contents of Van Houten's letter, which Augustus gave to Hazel, connect deeply with the themes of love, loss, and longing that permeate various literary works.
We encounter reflections on the nature of grief and the desire for togetherness in the midst of sorrow, as seen in the references to classic literature where characters express profound emotions through letters.
This corresponds with the experiences of Hazel and Augustus in their own lives and in the story's unfolding narrative. In the letter, Van Houten touches upon the existential resignation to a life of wretchedness, counterbalanced by a glimmer of hope for reunion and the continuation of love beyond hardship and even death.