Symbolism, Imagery, Allegory
Augustus's house is all decked out with inspiration. Yep, you know the kind. On every single surface of house, there are encouragements or inspirational phrases:
A wooden plaque in the entryway was engraved in cursive with the words Home Is Where the Heart Is, and the entire house turned out to be festooned in such observations. Good Friends Are Hard to Find and Impossible to Forget read an illustration above the coatrack. True Love Is Born from Hard Times... Augustus saw me reading. "My parents call them Encouragements," he explained. "They're everywhere." (2.23)
Like "The Heart of Jesus," the Encouragements are a tangible form of comfort. Even though Hazel and Augustus don't necessarily agree with them (and sometimes make hilarious fun of them), they know that they provide some measure of comfort and hope to Augustus's parents. When Augustus dies, Hazel even mentions them in her eulogy just because she knows that it will mean a lot to them.
Bottom line: everyone copes differently. And hey, to each his own.