The line is from a poem called simply “I am”, and here are its first three lines, written down, to my delight already, from memory:
“I am, yet what I am none cares or knows;
My friends forsake me like a memory lost:
I am the self-consumer of my woes"
(I got a few words wrong!)
I don’t know why these lines swirl away in my mind as much as they do. I suppose that this is one of the secrets of good poetry. Its rhythms and its juxtapositions of oddly-assorted words lead us away from the everyday into some distant realm of the spirit. "I am the self-consumer of my woes" speaks to me in a way I don’t really understand, but simply feel.
He was completely self-taught, working as a labourer in the fields to support his family, and then unhappily spent the last years of his life consigned to an asylum. I have just discovered that “I am” was the last poem he wrote. He must indeed have felt that his friends had forsaken him “like a memory lost”, so that he had to become “the self-consumer of his woes”.
Reading about his life, and its unhappy ending, I can at last begin to understand the meaning of these lines