I have a dim memory of my undergraduate days, in which I went on a fruitless search for a good one-volume edition of Shelley’s poems. There wasn’t one; not even in the excellent Penguin Poets series, under the general editorship of Christopher Ricks.

The reason, of course, was the amount Shelley wrote, and the length at which he often wrote. Look at the index of titles in this edition: only a little more than two pages long, in an edition with 600 pages of poetry (plus 70-odd of prose, not counting the introductions and dedications to the previous poems, and more than 200 pages of notes. One can only marvel at the amount of editorial work that has gone into this volume). One poem, The Revolt of Islam, isn’t included here, and that may be because its annotated 12 cantos, or 4,818 lines, would have added another 200-odd pages to the book.

Shelley’s prolixity made me back away from him when I was a student, and I suspect I am not alone. Byron may have gone on a bit, too, but at least he made jokes; and Keats was the better poet. Indeed, in Adonais, his lengthy elegy on Keats’s death, Shelley admits as much, even if the sentiment – “I consider the fragment of Hyperion, as second to nothing that was ever produced by a writer of the same years” – is somewhat guarded. It has to be said that there is something a bit hysterical about the tone of Adonais, even making allowances for Romantic expression (“O, weep for Adonais! though our tears / Thaw not the frost which binds so dear a head!”). Still, those were the times and the way one expressed oneself in them.

There is a world of difference between having to read a poet as part of your studies and picking one up for pleasure later, which is why this is such an important and definitive edition. It will suit both the scholar and the general reader. The editors have managed to squeeze in some unfinished poetry and prose works – in some cases they break off poignantly mid-sentence, but they are nevertheless worthy of inclusion. Some of the poems, such as “Dirge for the Year”, are all the more effective for their unexpected endings: “January grey is here / Like a sexton by her grave – / February bears the bier – / March with grief doth howl and rave – / And April weeps – ”. And that’s how the poem ends, almost as if anticipating The Waste Land (not to mention the similarly punctuated work of Emily Dickinson), not to mention Emily Dickinson.

One of the fascinating things about Shelley is that, while the diction may now sound archaic and high-flown, his political sensibility was ahead of its time. His atheism, to take just one of his revolutionary positions, was extremely courageous for the era, and bravely expressed, too. Just look at Prometheus’s opening lines from the eponymous poem, addressed to Jupiter (very often a stand-in, at one safe remove, for the Christian God): “Regard this Earth / Made multitudinous with thy slaves, whom thou / Requitest for knee-worship, prayer, and praise, / And toil, and hecatombs of broken hearts ... ” Once the phrase sinks in, it is difficult to get “knee‑worship” out of your head, not to mention “hecatombs of broken hearts”. He was good at invective; remember his couplet on the foreign secretary in The Mask of Anarchy: “I met Murder on the way – / He had a mask like Castlereagh –”

So this is Shelley’s triumph. He was hounded at the time for his progressive views, his overturning of the received pieties of the day; and while today the flame of progressive thought is flickering in the gales of intolerance and brute ignorance, we need Shelley’s example, and his exemplary anger, all the more.