Watts wastes no time on scene-setting. The first line states the idea, and the rest of the poem tests how far it stretches: God is a refuge, and help arrives before the prayer does. "Ere we can offer our complaints, / Behold him present with his aid!" Rescue here is not an answer to asking. It is already in the room. This is a version of Psalm 46, and its central claim is that security does not depend on circumstances. Mountains may be "hurled / Down to the deep" and nations may tremble, but "Our faith shall never yield to fear."
The poem works by setting two kinds of sound and motion against each other. On one side is chaos: "convulsions shake the solid world," the "troubled ocean" roars, the shores tremble. On the other is a quiet water image, "a stream, whose gentle flow / Supplies the city of our God." The heavy consonants of "hurled" and "roar" give way to the soft, sliding sounds of "gentle," "gliding" and "watering." The sea threatens from outside, while the stream runs inside the city. Safety is not the absence of water but a different kind of water.
Watts's grammar adds a note of defiance. "Let mountains from their seats be hurled" and "Loud may the troubled ocean roar" are not descriptions but concessions, almost dares. The speaker grants the worst in advance, and the poem then refuses to be moved. The last line, which promises to "sing / Defiance to the gates of hell," shows that this faith is not meek. "Satan" and "hell" also give the poem a distinctly Christian colouring.
The form supports the message. Every stanza has four lines of eight syllables, mostly iambic, rhymed ABAB. The beat is steady and unhurried, like a pulse that does not panic, and a congregation could sing and memorise it easily. Most rhymes are clean ("saints/complaints," "roar/shore," "abide/tide"). A few rhyme only on the page: "flow/through" and "love/move" look like rhymes but do not sound like them, and "there/fear" is only approximate. A tune would presumably smooth over such looseness, and it hardly dents the poem's solidity.
The middle of the poem is its most interesting stretch, because the picture of God grows more unsettling. At his voice "the nations melt, the tumult dies." He "breaks the bow," "cuts the spear" and burns chariots, and he "awes the trembling world to peace." That is peace imposed by thunder. The exclamation "What desolations he hath made!" sounds like admiration with a shiver in it. Then the noise stops. "Keep silence, all the earth, and hear" clears the stage for the only lines in which God speaks: "Be still, and learn that I am God." Where many English Bibles say "know," Watts writes "learn." Stillness becomes something like a lesson, and the roaring ocean of the earlier stanzas is quieted so that the lesson can be heard.
The address also shifts as the poem goes on. It begins by talking about God ("his saints," "his aid"), moves to the first-person voice of God himself ("my throne in Zion stands"), and ends with a direct prayer: "O Lord of hosts, almighty King!" The final stanza turns from describing trust to speaking it aloud. Its closing rhyme, "dwell" with "hell," places those who live near God's presence at the very edge of the worst imaginable threat and has them sing anyway.
Watts is remembered as a major English hymn writer, and the poem shows why. It takes an ancient scene of earthquake, flood and war, with place names like Zion and Jacob, and makes it speakable for ordinary singers. Simple, mostly one-syllable words carry huge events, and "we" and "our" invite every voice in the room to claim the ancient promise as its own. What lasts is the central picture: a small, calm voice that stays steady while the whole world shakes.