Consider the possibility that this is a celebration of someone on the verge of death who finds that all the "flames" (power) of their "name" (self, identity) is a bright as ever even though they stand at the end of days: they shall live in that ongoing flame though they die.
As all things around us are malleable, we are not; we can be bent but not broken, we can be burnt but not consumed. The human spirit and an individual's impact on reality is eternal, although the physical remains can vanish. The "ships" burning on the shores are passing by; we stand in our reality, in our consciousness, and remain constant while everything around us changes. We can change ourselves, although with great effort, but the world will not change us without consent.
The title is interesting to me, since St. Anthony's Fire is a popular name for ergotism- basically poisoning by the fungus ergot, which can lead to hallucinations. (LSD is a lab-created version of ergot) I agree with the interpretations of the poem above, but I wonder what the title means to the author?
I agree that the poet is indicating how physical objects, however old, can be destroyed, where as our spiritual constructs - memories and past actions - remain with us. The "indestructible weight" which "follows" the narrator reminded me of Jacob Marley's ghost in "A Christmas Carol", forced to carry the chains he forged in life with his selfish deeds.
The tone of the last stanza definitely implies a dark feeling with words like "indestructible weight" and "follows me." We are usually uncomfortable with excess weight or someone following us; but, at the first reading, I focused on "old things" being burned. To me this meant that old things are of worth to us as we progress through life or move from one phase to another. Even though the tone is dark with his response in the second stanza, the word "quenched" suggests that something has also been satisfied; yet, the full phrase, "quenched heart of night" would simply mean at the darkest moment of night when one might be confronted with his/her deepest thoughts that cannot be forgotten. In the morning, the sun's light might shed forth light on the subject, but for the moment, in the poem, he is caught in "the evening of my name" on a "shore of a dark sea" facing either an end or a beginning. . . we don't know for sure.
It also seems that the man is in his twilght years--"the evening of my name"--and reflecting on things in the past that cannot be undone, full of regret and possibly even bearing the burden of a guilty conscience.
My response to the poem is to see a distinction being made between the material world and the spiritual world. The world that exists within the spirit of the speaker cannot be burned and will persist, while the material world with all its "things" grows old, decays, burns and disappears.
Another way of saying this is to say that the soul is permanent and the material world is transient.
As the previous posts have suggested, this permanence of soul carries a cost. For its permanence, the soul cannot be escaped.
I too was struck by the last line. My reaction was that everything bad that happens to us weighs on us for all of our lives. These events can weigh us down, and burn through us. It is actually very sad. It makes me think of depression, and the effect it has on us.
For me, this means that everything we do stays with us. We cannot escape our past. The author seems to be contrasting ourselves (and perhaps our souls) with the physical things in the first stanza. Physical things can be destroyed but what we are and what we have done stays with us forever. This could be good and bad. I'm ambivalent about what the poem means in that regard. Is "indestructible weight" a good thing because it's indestructible or bad because it weighs us down?
There is a deliberate contrast created between the flames that the speaker is viewing, which devour, destroy and eat up the "old things" that are described and the way in which the narrator wishes that various parts of his own life could be eaten up and destroyed by fire in the same way. The poem points out the impossibility of going back and changing or erasing various parts of our past that we want to ignore or not to acknowledge.