The great American poet John Berryman would have been 100 today, had he lived. One of the things most people know about him is that he did not. He killed himself at 57 – after a lifetime of chaos, alcoholism, mental illness and extremely hard work.

During his lifetime he was competitive. One of his late collections was called Love & Fame, and he was very interested in both. When Robert Frost died in 1963, Berryman’s reaction was: “It’s scarey [sic]. Who’s number one? Who’s number one? Cal is number one, isn’t he?” Cal was Robert Lowell.

That was probably right. Since then, Berryman’s reputation has held up – though he has never quite been number one. He is, if this makes sense, a major cult poet – or a cult major poet; feted in part for the manner of his death or his association with a generation of poets who liked to think of themselves as maudits. But he is famous, and he is loved. I think he deserves to be more of both.

What he is most remembered for, though there are glories in his other work, is The Dream Songs, which you could think of as a poème-fleuve: he found (and there is an American tradition of this stuff going back to Whitman) an expansive, accretive, flexible open form that allowed him to somehow drift net the jetsam of a life and the flotsam of his place in the century.

Berryman set out the situation of the poem in an introduction to the 1969 edition (the first part of the poem had appeared as 77 Dream Songs five years previously):

The poem then, whatever its wide cast of characters, is essentially about an imaginary character (not the poet, not me) named Henry, a white American in early middle age sometimes in blackface, who has suffered an irreversible loss and talks about himself sometimes in the first person, sometimes in the third, sometimes even in the second; he has a friend, never named, who addresses him as Mr Bones and variants thereof. Requiescant in pace.

After prentice work that saw him labour in the shadows of (among others) Yeats, Berryman found the form: a sort of broken sonnet in three stanzas. Lowell – under Berryman’s influence, it’s fair to assume – tried something similar with his big, open, much-revised sonnet-sequence Notebook and History. But Berryman’s sequence was neither notebook nor history – it was a fantasia, wild, spiky, self-teasing, exuberantly free in tone. It evidences deep reading – Berryman was a scholar-poet and most of his life was spent in institutions, usually academic ones – but slaloms around literary decorum. “Rilke was a jerk,” he exclaims at one point. His protagonist Henry – “huffy”, in the first word of the poem – isn’t allowed the dignity of classical verse; and nor, for that matter, is classical verse. Henry’s “plights and gripes” are “bad as Achilles”.

Berryman, along with Lowell, was identified with the movement known as “Confessional Poetry” – and, like every poet ever identified with a movement, rejected the label. His life informed his poetry. And he did, notoriously, say: “The artist is extremely lucky who is presented with the worst possible ordeal which will not actually kill him. At that point, he’s in business.” But it’s the art, not the suffering, that matters: as the title suggests, the material went through what Freud called the “dream-work”. The art redeems the suffering elsewhere.

Still, here is poetry that for all its eccentricities of diction and action, is close to life: “Henry, to some extent, was in the situation that we are all in in actual life,” Berryman said, “namely, he didn’t know, and I didn’t know, what the bloody fucking hell was going to happen next. Whatever it was, he had to confront it and get through.”

Henry is in a state of perpetual transformation. Now he’s a cat, now he’s a yogi, now he’s a motorboat. Now he’s a crazed veteran holed up, First Blood style, in the mountains. He takes LSD. He meditates. He drinks. He gets on the wagon (“Sober as a man can get, no girls, no telephones”) and falls off it. He suffers hangovers (“Sick at 6 & sick again at 9 / was Henry’s gloomy Monday morning oh”) and gastric discomfort. Berryman was an alcoholic, and the poem does not leave that out: it is sometimes jokily evasive (“Man, I been thirsty”); sometimes full of shame; sometimes mired in horror, as in Henry’s recurring dream of having killed someone (“He knows: he went over everyone, & nobody’s missing. / Often he reckons, in the dawn, them up. Nobody is ever missing”). At one point, in a sequence of Songs called Op Posth, he dies; and that by no means shuts him up. Henry moans and mourns, he flashes and yearns, he rails against the Almighty (“God’s Henry’s enemy”), he clowns and sulks. And he lusts – oh boy does he lust. “Love her he doesn’t but the thought he puts / into that young woman / would launch a national product / complete with TV spots & skywriting … Vouchsafe me, O sleepless one, / a personal experience of the body of Mrs Boogry / before I pass from lust!” For Henry, “the sweet switch of the body” is an urgent call: he is “tasting all the secret bits of life”.

Berryman is (relatively) unusual among poets because he’s funny. Daniel Swift, who has edited some handsome centenary reissues of Berryman’s work for Farrar, Straus & Giroux in the US (Faber, feebly, isn’t marking the occasion in the UK), suggests that his status as a minor major poet – his not quite getting his due – is in part down to this. People still don’t think funny poets are as important as the non-funny kind. But Berryman is the proper sort of funny: the funny that is involved with heartbreak. His friend Lowell called him a “great Pierrot … poignant, abrasive, anguished, humorous” – and that seems to me an unimprovable description of the mix. The Dream Songs is a slapstick Book of Job. Most of what you might call the Greatest Hits – the lines and poem chunks most quoted in isolation – are funny. “Life, friends, is boring …”; “Bats have no bankers and they do not drink / and cannot be arrested and pay no tax / and, in general, bats have it made”; “Bright-eyed & bushy-tailed woke not Henry up”; “If I had to do the whole thing over again / I wouldn’t.”

One of his lines – even though I have no idea to what it refers – makes me laugh every time I think of it.

– Are you radioactive, pal?

– Pal, radioactive.

– Has you the night sweats & the daysweats, pal?

– Pal, I do.

– Did your gal leave you?

– What do you think, pal?

– Is that thing on the front of yourhead what it seems to be, pal?

– Yes, pal.

But funny as Berryman is, he’s a poet of mourning. The Songs circle around and fret, as Berryman said, at “an irreversible loss”. The primary loss is Henry’s father, who like Berryman’s own biological father, John Allyn Smith, took his own life when Henry was a child (christened John Allyn Smith, Jr, the poet took his stepfather’s name). But grief, in The Dream Songs, is more general. Sunt lacrimae rerum. There is the grief of deep time: “a grave Sienese face a thousand years / would fail to blur the still profiled reproach of”. There is the anguish of losing contemporaries (“I’m cross with god who has wrecked this generation”). There is the bewildering childlike fear of watching the older generation go (“The high ones die, die. They die. You look up and who’s there?”). And there is a primal sense of an irreparable “departure” – Berryman wouldn’t have been crude enough to identify it as birth-trauma or Man’s fallen condition – that afflicts not just Henry but all of us. As he puts it in the closing lines of the first Song: “Once in a sycamore I was glad / all at the top, and I sang. / Hard on the land wears the strong sea / and empty grows every bed.”

I have loved Berryman’s work since I was a teenager. And the species of love I have for it is quite different from that I have for almost any other poet. For several years I toted around a stained and wracked paperback of 77 Dream Songs in whatever passed for my satchel or hand luggage. My valediction and thanks to my favourite teacher at school was a hardback copy of Faber’s big blue edition of The Dream Songs. I spent a good chunk of the (small) advance on my first book on a US first edition of the 77. Before YouTube came along, I was searching sound archives and poetry libraries for recordings of him reading (there’s a great one from the Academy of American Poets, in which he tells a joke about a kid trick-or-treating and completely screws up the punchline). When my wife wants to give me a serious present, it’s a Berryman first edition. My cat, for Pete’s sake, is called “Henry” because of Berryman (Henry, in the poems, is frequently a cat: “I am Henry Pussy-cat! My whiskers fly!”).

I’m trying to get at something about his particular appeal. People who like Berryman really like him. When Berryman fans identify one another in, say, a crowded party it tends to end in a quote-off and a fast friendship. There are 20th-century poets most of us will acknowledge as better, but there are few with whom one so strongly feels one has found, in Berryman’s preferred epithet, a pal. You find in him remarkable technical command, deep and riddling allusiveness, killer gags and an antic harlequinade of aspects and personae that recalls Looney Toons as much as it does The Waste Land. But you also find a voice: this character Henry, who is half Berryman and half not, and who lives on the page and speaks to you. The voice looks easy to imitate or parody – with its fractured syntax, its tics and ampersands – but, as many who have tried discover, it isn’t.

Is there another poet in the language who can be said to be so companionable? Berryman, and he was pretty plain about it, rejected TS Eliot’s idea of the impersonality of poetry: he talked about personality as an organising principle of the Songs. Berryman’s pre-Dream Songs breakthrough, “Homage to Mistress Bradstreet”, is half seance, half love-affair: the poet’s voice entwines with that of the 17th-century poet Anne Bradstreet whom he conjures up, and they flirt. Another key to the directness of his appeal is the way in which he flouts John Stuart Mill’s old idea of poetry as being not heard, but overheard. Here is poetry that is not only heard: it buttonholes you.

About that blackface. I think it is fair to acknowledge that the racial politics of The Dream Songs are what academics like to call problematic. But it’s fair, too, to make clear that “problematic” in this case means complexly troubling rather than being a crude euphemism for “racist”. Henry is sometimes in blackface. The dynamic of his relationship with his unnamed friend is shaped by the call-and-response of minstrel patter. “Mr Bones” is a stock end-man (the clownish figure at either end of the semicircle in which minstrel performers traditionally sat), and the Songs are littered with “darky” patois. But we have to remember that as Berryman cautioned, “many opinions and errors in the Songs are to be referred not to the character Henry, still less to the author, but to the title of the work”.

I remember having a long argument, years ago, with a friend brought up in Washington who regarded any tinge of minstrelsy as anathema. The position I took was that this was a work of self-laceration and self-reproach – that here was a poet determined to put this character, halfway a portrait of himself, messily in the wrong and that blackface was a way of doing so; that her offence, directed at Henry and through him at Berryman, was in other words an intended effect. Not sure I quite buy that, now: it’s to under-read the poem, to ignore that, at the time of its writing, blackface was not as taboo as it is now, and not to acknowledge the prankish energy that the minstrel material gives it.

But I think it can be said with confidence that racial mockery is not the point of the blackface in the Songs, nor even a point of it. It is doing something different there, and such offence as it gives, well …

Where did it all go wrong? There ought to be a law against Henry

– Mr Bones: there is.

Berryman’s only novel was about an alcoholic drying out. It was called Recovery, and it wasn’t finished because he didn’t. On 7 January 1977 Berryman walked along the outside of the covered Washington Avenue Bridge in Minneapolis, climbed on the railing, leaned out and let go. Some accounts had it that he made a gesture something like waving goodbye.

Requiescat in pace. And happy birthday, pal.