The poem
This celestial seascape, with white herons got up as angels, flying high as they want and as far as they want sidewise in tiers and tiers of immaculate reflections; the whole region, from the highest heron down to the weightless mangrove island with bright green leaves edged neatly with bird-droppings like illumination in silver, and down to the suggestively Gothic arches of the mangrove roots and the beautiful pea-green back-pasture where occasionally a fish jumps, like a wildflower in an ornamental spray of spray; this cartoon by Raphael for a tapestry for a Pope: it does look like heaven. But a skeletal lighthouse standing there in black and white clerical dress, who lives on his nerves, thinks he knows better. He thinks that hell rages below his iron feet, that that is why the shallow water is so warm, and he knows that heaven is not like this. Heaven is not like flying or swimming, but has something to do with blackness and a strong glare and when it gets dark he will remember something strongly worded to say on the subject.
I love this poem. It's wonderful imagery really gives the reader a view of a seascape. Bishop paints a beautiful canvas marred only by Man's design. The lighthouse stands for Man's interference, ignorance, and domination. I believe that Bishop was expressing her disapproval of the attitudes and narrow-minded beliefs of Western Culture (mainly to do with Christianity) and their appearance on the face of natural beauty and acceptance--they're more like a pock-mark or a black head rather than some guiding light (which is cleverly embodied by the image of the lighthouse).