The speaker lives in a high-rise and looks out at the world from a window, feeling cut off from the people in the buildings around him. He puns on "apartment" and "apartness" to show how close neighbours can still feel like strangers: no window offers a clue to connect with, as in a crossword.
Beyond the buildings, he turns to nature and sky. Alder leaves, birches, wind and a pale, washed-out sky are described with close, tactile images, so the natural world feels more alive than the human one. Meanwhile, the poem notes that building has gradually blocked parts of the view, such as the school roof, though the cathedral tower and distant horizon remain.
The last stanza gives the poem its weight. For fourteen years he has watched white ships glide past from the seventh floor, and he calls his flat an "oratory," a place of prayer. The mood is quiet, solitary and reflective, with loneliness softened by a settled, almost devotional attachment to this view.