The tone at the opening of the poem is giddy and excited. After all, this is a somewhat glib speaker who is readying himself for dinner at the home of someone he doesn't know, who can smart-aleckly refer to the "poets / of Ghana," who is prone to "stroll" and "casually ask" for cigarettes, and who can "practically" go "to sleep with quandariness" over the simple decision of what book to buy a friend. This is not a speaker burdened with metaphysical deliberations about the meaning of life.
Even when he sees the "NEW YORK POST with her face on it," he refuses to break into discourse on the brevity of human life, "thinking," instead, in visual and sensory images. He recalls an instance when he heard Billie Holiday sing so sweetly that life itself seemed to halt in deathly pause while "everyone and I stopped breathing." Up to this point, he had offered the reader an ontological account of selfhood based largely on a narrative retelling of the way the individual fragments of his day melded into a mysteriously unified whole. But at this juncture, where anticipation and profound loss meet head on, the collision results in image, scene, a moment of experience which itself is of ultimate value. The present moment and the remembered one do not require metaphysical rumination in order to clarify them. That kind of deliberation has preceded the poem onto the page: the understanding that life is unpredictable and crass, capable of imparting immense pleasure and equally formidable pain. Although O'Hara may very well have agreed with the Heraclitean conception of a universe forever in the process of change, he would never use Heraclitus's fragments as poetic epigraphs (as Eliot did) or allow such thinking to impose an overtly philosophical structure on his work. O'Hara has already decided on these epistemological and ontological issues before the poem began. And more importantly, they were first of all personal values, which naturally (but secondarily) gave form to artistic values.
From "Everything the Opposite" in Frank O'Hara: To Be True to a City. Ed. Jim Elledge. University of Michigan Press, 1990.