Leaving a favourite hill is a small event, yet Edward Thomas treats it as a quiet loss. The speaker walks down a chalk slope for "the last time" and realises that something has already gone. The hill is as fair as ever. What has vanished is the hope that once made his heart race at the sight of it. The poem's central idea is that hope and love are different things. Hope fades with the years, but love grows through time and, in the last lines, answers the loss with a deeper feeling.
The opening stanza captures that early hope. It is hope with no object: "Hope for I knew not what." The vagueness is the point. The young speaker expects a revelation, as if "scaling its steps of chalk" will show him "something no other hill / Ever disclosed." The line breaks help the excitement along. "Fast beat / My heart" tips the beat over the line ending, so the heart seems to jump ahead of the sentence. The hill, with its "tall slope" and its yews, becomes a promise.
The realisation arrives in the middle of the poem, and its grammar is telling. The change is "infinite" and "late unperceived", then "suddenly, shows me plain". Years of gradual loss are recognised in a moment, and the commas around "suddenly" make the reader pause as the speaker does. He then separates hope from lesser losses. "Health" and "cheerfulness" can "come and go again, / As often one brief hour witnesses", so moods shift within an hour and are easy to recover. Hope is different. The dashes and the aside hold back the main statement, so that "Just hope has gone for ever" lands more heavily. "Just" is a small, almost offhand word, and the offhandedness makes the loss feel more final.
The form is deliberately plain. There are six quatrains rhymed abab, in a loose iambic line of four beats, and most of the words are short and everyday. The sentences keep spilling over the ends of lines and even of stanzas. "Never will" closes one stanza and its verb waits in the next, and "this year" hands over to "The twelfth". The effect is of someone thinking aloud and working out what he feels as he speaks. The rhymes arrive so quietly that they feel like a natural pause, and some, like "fair" and "year", are only approximate.
The ending turns on a change of tone. "Perhaps" opens the future, and the speaker admits that "the future and the maps / Hide something I was waiting for." The maps are a good choice of word. They are flat and practical, the opposite of the hill's mystery. Then comes "One thing I know", firm after all the uncertainty of "I knew not what" and "Perhaps". What he knows is that love grows "with chance / And use and time and necessity." The repeated "and" piles the nouns up like ordinary days. Love here comes from habit, accident and need, not from wonder.
The final lines also quietly contradict the earlier ones. The speaker said his heart would "Never" beat as it once did at the sight of a hill, yet the poem closes on "louder the heart's dance / At parting than at meeting". The heart does beat again, but for a different reason. At first it raced at what might be ahead, and now it aches at what is being left behind. The slightly stiff inversion of the last line, ending on "be", gives it the sound of a proverb, as though the speaker is stating a hard-won rule.
The poem matters because it refuses easy comfort. It does not claim that cheerfulness will return and make up for the lost hope. It also does not wallow, since it finds something true to put in hope's place. Many readers will recognise the experience of leaving a school, a street or a house and finding that the place has become dearer just as the excitement has gone. Thomas makes that feeling clear with short words and a single hillside.