This intriguing poem does not offer us a specific explanation of the event that birthed it. However, if we consider the poem as a whole and the various themes that run through it, perhaps we can move towards a tentative idea of the situation that triggered the poem. Consider the opening lines of the first stanza:
The room was suddenly rich and the great bay-window was
Spawning snow and pink roses against it
Soundlessly collateral and incompatible...
The reference to the snow and later on to the "fire" with its flames making a "bubbling sound" suggest that the event that triggered the poem occurred during winter with a sudden snow shower that forces the poet to see a huge number of contrasts in his setting, or things that are "incompatible." Not only do the "pink roses" seem incongruous given the snow outside, but also the fire is both "spiteful" and "gay." The richness of life, as established in the first line, seems to owe itself to the juxtaposition of "Incorrigibly plural" and seemingly "incompatible" emotions and objects. This epiphany perhaps was triggered through the winter day that the poet is describing.