"The Pension Grillparzer" is Garp's first real writing effort and, as Jenny so eloquently states, "the sort of story she'd expect a boy without a proper family to make up" (6.68). This is fitting, if not wholly supportive, because Garp is a kid without a "proper family." Right away, then, the story is a symbol for its writer. To this end, we're told:
Helen would later say that it is in the conclusion of "The Pension Grillparzer" that we can glimpse what the world according to Garp would be like. (6.69)
Hey there, title of the book—nice to see you. Importantly, here a certain circularity to Garp's life is implied: In his first story, we can "glimpse" who Garp becomes later on. Or, put another way, who Garp becomes in the end is already present when he's much younger. So while there are ways this is a story about progress—be sure to read up on Garp in the "Characters" section for more on this—the "Pension Grillparzer" also works symbolically against progress.
Does this feel a little absurd to you? This sort of mixed message? Consider this: The death of Charlotte inspires the most important passages in "The Pension Grillparzer." At first, all Garp has is a ridiculous situation and silly cast of characters. But then Charlotte gets sick, and Garp's first-hand witnessing of her decay provides the emotional foundation for the story. "The Pension Grillparzer" treats death like a wily trickster, and in this, we can see echoes of the absurdity of Charlotte's demise—she does everything right, like using contraceptives and saving her money, but still winds up dead.
Again, then, we see progress split, both happening and not happening. Death is a sort of progress, an end of the line we all head toward. But at the same time, no matter what Charlotte does in life, she can't avoid the certainty of death, and because of this, her life lacks progress, too; she can't move herself beyond her inevitable demise.
Considered all together, we can see "The Pension Grillparzer" as representing a bind between life and death, as poking at the idea of progress and seeing how it is both possible and impossible. The story becomes Garp's favorite work by the end of his career. Now jaded by life's experiences and his numerous brushes with death, this simple story is like "going back to the beginning and getting a fresh start" (18.368). But as we know from the quote about Helen above, the beginning is already present in the end of Garp's life anyway.