Two small images sit side by side here, and the poem lets them quietly comment on each other. In the first, a moth by a fire "begins to see." We usually think of moths as drawn blindly toward flame, so the idea that the fire gives it sight is a surprise. Closeness to light might bring understanding, even if it also brings danger.
The second image turns to the speaker, who sits with "bones unread / like impossible letters." The body becomes a kind of text, something that holds meaning but can't yet be deciphered. The word "impossible" suggests the speaker feels shut out from their own self, unable to make sense of what lies beneath the skin.
The mood is still, private, and a little eerie. The moth is beginning to understand something, while the speaker is not. The poem seems to wonder what it would take to sit close enough to the light to finally read.