The speaker sits in a church, surrounded by stone carvings of people he doesn't recognize, and falls asleep during most of the sermon. The poem seems to catch the odd, half-dreamy state that follows: he wakes with a "broken" face and a head that feels like an ancient relic resting on "two pillars," which could be his shoulders, or perhaps his neck, or the columns of the church itself.
The key move is the blurring between the living man and the stone figures. By the end he has become one of them, an old, weathered thing set on a support. The sleeping face looks cracked and worn, the way carved faces in old buildings often are.
The mood is quiet, strange, and a little humorous. There's a hint of drowsy guilt about nodding off, but also a sense of time pressing in: the church is old, the figures are anonymous, and the speaker feels briefly like part of that long, silent line of people.