The Sanctity of the Quotidian
First and foremost, Billy Collins writes poems about everyday life. His work proves so accessible to readers because he focuses upon situation to which anyone may relate. And he accomplishes this while simultaneously elevating these ordinary experiences with a sense of reverence. "Litany" makes comparisons between household objects and the narrator's affection for his lover. While some of these objects could ordinarily be considered humble or even insulting, in Collin's imagination they become symbols of beauty, goodness, and merit.
Similarly, Collins defies the boundaries of supposedly low and high culture by borrowing from one group to improve the other. He explains the intellectual or the intangible through the material and the ordinary. For example, "Flames" features Smokey the Bear, a pop culture icon. Despairing after people ignore his message, Smokey gives up and burns down a forrest. Effectively Collins takes the pop culture image and reverses the symbol from optimistic protection to cynical despair. Since Smokey is an icon especially well-suited to children's education, his depiction in Collins' poem reflects the entropy of hope as a person matures.
Wrestling with Meaninglessness
Although Collins often writes hopeful poems, he remains transparent about his own frustrations with the meaninglessness of life. "Forgetfulness" is the best exmaple. Collins laments how he cannot seem to remember the things he wishes he could and remains conscious that he's losing pieces of his life in his memory, but he doesn't remember enough to know which. He wants to be able to hold onto all of it, a lifetime, all at once. As he mulls over the problem, Collins draws a comparison with how even a person's life is relatively soon forgotten after their death. Nothing lasts. In opposition to the temptation to give up in light of this revelation, Collins asserts how a person must lean into the appreciation of life because nobody else will be able to appreciate their life in the same way.
Embracing the Present
Since he writes about ordinary life, Collins easily incorporates elements of the personal in his description of the present. To him, each tableau is inherently personal because he deliberately cultivates mindfulness of the present. This is why he so effectively praises the beloved in "Litany" using comparisons to household objects. Also, this is how the narrator of "Forgetfulness" combats the terror of forgetting and being forgotten -- by appreciating the present moment. In fact Collins writes "Fool Me Good" explicitly about his commitment to being present. He outlines this commitment as an acceptance of responsibility in order to love himself and those around him better. Since people are lonely, they often search outward and beyond, neglecting the immediate and available.