In the previous post Bryan links to, he says: "I am falling in love with the melancholy late Victorian/Edwardian sense that we can never be fully alive." He cites a passage from Conrad about "the fatal imperfection of all the gifts of life, which makes them a delusion and a snare."
Is it the imperfection of the gifts or our imperfect ability to fully appreciate them? Thomas's 'I cannot bite the day to the core' points to the insufficiency of the bite, not the day. Saint Augustine saw in our dissatisfaction proof of our longing for God: "Thou hast created us for Thyself, and our heart is not quiet until it rests in Thee."