Herbert, a priest as well as a poet, sets out to define prayer and never gets around to a main verb. From the first word to the last, the fourteen lines are one long run of descriptions piled side by side, each replacing the one before. The structure makes the poem's argument. Prayer is too large for a single definition, so the poem keeps trying new ones.
The opening images stretch from the domestic to the cosmic. Prayer is "the Churches banquet", a shared meal, and then "Gods breath in man returning to his birth". The second phrase seems to echo the idea of God breathing life into humanity, with prayer sending that breath back where it came from. Then comes a sailor's image: "The Christian plummet sounding heav'n and earth." A plummet is the lead weight on a line used to measure the depth of water, and "sounding" is the measuring. Prayer here is a way of finding out how deep things go, in both directions. "Angels age" is the most puzzling phrase, and the poem doesn't explain it. Judging by the context, it may suggest a span of time that belongs to angels rather than to us.
The second quatrain turns violent. Prayer is an "Engine against th'Almightie", a siege weapon, and a "sinners towre", a place to climb to or hide in. It is "Reversed thunder", which neatly flips the usual direction: thunder comes down from God, and here the noise goes up from us. Then there is the "Christ-side-piercing spear", an image from the Crucifixion, so prayer can wound as well as comfort. The line "The six-daies world-transposing in an houre" squeezes the whole of Creation into sixty minutes, and "transposing" carries a musical sense that prepares for "A kinde of tune, which all things heare and fear". After these lines prayer is no longer polite or passive. It is dangerous, powerful and audible to the whole universe.
At line nine the mood changes, and so does the sentence. "Softnesse, and peace, and joy, and love, and blisse" is the one line made only of abstract feelings, and the repeated "and" slows everything down, like someone counting blessings. After the weapons, the poem rests. The images that follow mix the ordinary with the extraordinary. "Exalted Manna" is the bread that fell from heaven in the Bible, raised to a higher level. "Heaven in ordinarie" suggests heaven as everyday fare. "Man well drest" suggests that a person at prayer is properly clothed for the occasion. Then the eye lifts to "The milkie way, the bird of Paradise", and the ear to "Church-bels beyond the starres heard".
The form helps all this feel controlled. It is a sonnet in iambic pentameter, and the rhymes run abab, cdcd, then efFe, with a closing couplet. Because the images arrive so quickly, the regular beat gives the reader something to hold on to. Herbert also varies the pacing: the heavy, comma-cut lines of the first eight lines give way to the long, flowing list of line nine. The couplet pairs "bloud" with "understood", spelled so that the rhyme is visible. Linking "the souls bloud", the life force, with understanding hints that prayer is both felt and known.
The final line is the cleverest. After twenty-odd metaphors, the poem ends with "The land of spices; something understood." The spices are a last exotic image, but the semicolon then cuts in and the language goes plain. "Something" is deliberately vague, the least impressive word in the poem, and the vagueness is the point. The ornate list admits, quietly, that it hasn't captured prayer. What remains is a simple idea: prayer is the moment when someone is understood.
That is what makes the poem worth reading. It is a definition that knows definitions fail, and it turns that failure into its subject. It also changes what we expect of prayer. The poem shows it as something fierce, tender, cosmic and domestic, but in the end it doesn't value eloquence or power. It values being understood, and the poem makes that feel more moving than any of the grand images that came before.