Before the English begins, Shelley gives us the opening of the Greek line in transliteration and then breaks off with "k.t.l.", the abbreviation for "and so on". It is a modest signal. What follows is not a grand statement but an ancient voice carried into English, and the voice belongs to someone weighing two ways of living: on the water or on the land.
The first four lines make the sea sound irresistible. When the wind stops, the water is "azure", the deep has "smiles", and the soft sounds of "serene and tranquil" seem to smooth the surface further. Yet the speaker says this calm tempts "my unquiet mind". "Tempt" is a loaded word, and "unquiet" suggests that the pull of the sea is partly a symptom of the speaker's own restlessness. Then the dash and the "But" break the mood. The sea's colour drains to "gray", and "deep" hardens into "abyss". Sound takes over, with the "roar" of the ocean, foam that "Gathers" and waves that "burst". The sentence spills across line endings in the same way, so the grammar seems to flood just as the water does.
The land is not offered as dull safety. The speaker retreats to "the home / Of Earth and its deep woods", and the woods have their own wind and their own noise. "When winds blow loud, pines make sweet melody." The same force that threatens a ship becomes music among trees. That line rhymes with "sea" in the next, so the sweet and the dangerous are tied together in one couplet, and the poem quietly admits they are the same weather seen from different places.
Next comes a sailor's life, and the sentence is built to make the reader wait. "Whose house is some lone bark, whose toil the sea, / Whose prey the wandering fish" repeats "whose" three times and gives the sailor a house, a job and a catch, though each is hardly more than a drifting boat, an endless struggle and something that slips away. "Lone" and "wandering" add isolation and aimlessness. The verb is held back until the next line, where the sailor "an evil lot / Has chosen". The word "chosen" matters. The speaker is not pitying a victim so much as judging a decision, and there may be a little self-satisfaction in it.
The ending is a deliberate change of pace. "But I my languid limbs will fling" twists the normal word order so that "I" comes first, set against the sailor. "Languid" and "fling" pull in different directions, one slack and one abandoned, which fits a body dropping onto the ground in relief. The "plane" tree and the "brook's murmuring" bring in soft m sounds that echo the stream. The last line is balanced on its "but": "Moves the calm spirit, but disturbs it not." Its paradox is gentle. Moving and disturbing are not the same thing, and the brook is allowed to stir the mind without unsettling it. The word "calm" has also changed owner. At the start it described the sea's surface, tempting from outside. Now it describes the speaker's spirit, which is the only kind of calm that lasts. The rhyme helps too, because the flat final "not" answers "lot", so the sailor's fate and the speaker's peace are paired at the poem's close.
The form is worth noticing. Greek verse of this period did not rely on rhyme, so the rhyme is part of how this English version recreates the poem rather than copying it. It runs in iambic pentameter over fourteen lines, though the pattern, ABAB CDCD, then a couplet, then FGGF, follows neither of the familiar sonnet schemes. The shape feels like a sonnet's argument with its own arrangement: two quatrains of attraction and recoil, a couplet that turns on the pines, and a closing sestet that settles the speaker under the tree.
That is where the poem earns its place. In fourteen lines it makes a small, believable argument about temptation, risk and contentment, and it avoids a simple moral by letting the land be noisy and the sea be beautiful. It is also a useful poem for students of translation. It shows that a translator makes choices of rhyme, word order and tone, and that a good version can read as a poem in its own right while carrying the thought of an older one.