The final poem in James Lasdun's last collection, Landscape with Chainsaw, had the speaker giving up poetry for the homesteader's life  "goats, organic lettuce, / that's the project"  like some back-to-front Robert Frost, opting for "the crack and grain / of real things" over their representation in words. "Now you can / just be their names again: / bluestone, shiplap, whatever. / And if I write, it'll be with a seed-drill; / a quatrain of greens per bed, no sweat." Reviewing the book, I wrote that I hoped Lasdun was having us on about laying down his pen. That was 11 years ago. What happened is that he gave up the poems for prose, and has published two novels (The Horned Man and the Booker-longlisted Seven Lies), three collections of short stories, assorted reviews and essays and a film script. A memoir is due out early next year.

As a prose writer, then, Lasdun has had a productive decade (though one can't help wondering how those goats and lettuces have fared). But it's a great pleasure to have some poetry again  Water Sessions is a collection of fine psychological acuity and astringent beauty. He acknowledges the hiatus here, in "The Ruined House", where a visit to a crumbling Italian village, its farmhouses deserted by the former peasants who lived and toiled there under feudal bonds, prompts a reflection on how "I had given up / a servitude of my own / to a no less exacting padrone; / Oh, I had broken / strong indentures, forsaken / the path of glory, / the discipline of the line, / for these paths of least resistance; / the sentence for the sentiero "

That shift from outer landscape to inner is a familiar Lasdun manoeuvre, and the physical landscapes here  mostly New England, where he's lived for 25 years  are as sharply observed as ever. Observation, it seems, leads inevitably to introspection. In "Bittersweet", the use of literal roots to suggest metaphorical ones is not exactly surprising, but it's effective because it's grounded in clear and precise description. The roots of the all-but-unkillable weed the speaker is trying to eradicate from his garden  "blood-bright, trailing their corpse-hair capillaries"  stand also for a series of inheritances (genetic, psychological, cultural) that aren't chosen and are impossible to renounce:

I yank them out
only to find they've coiled right
down through the shale
into solid bedrock,
leaving a lizard tail in each crack
potent enough to grow the
whole lizard back
just in case there remained any
doubt, any question
as to the error, the sheer utter
folly of planting
a garden of one's own
where bittersweet has grown.

The book centres on questions of identity  many of the poems constitute a reckoning with the speaker's place in the world, as a middle-aged man, as an immigrant to the US, as a parent learning to live with the death of his own father (the architect Denys Lasdun, to whom the volume is dedicated). Where Landscape with Chainsaw had a fine sense of the absurd in its poems of self-doubt, the overall tone here is less jocular, with sharper accents of guilt and shame. When the speaker's young son, in "The Question", asks him "Dad, / Is America good or bad?", his first impulse is to indulge in the standard parental equivocation when faced with the shaming innocence of one's own children: "That depends / on what you mean by 'good' or 'bad' / or for that matter 'America'." In the end, though, the inner monologue can find no outer manifestation and he is unable to answer: "something stalls me  as if after all I'd pledged silence / or struck some nocturnal pact / over whatever act, / doubtful or downright wrong, / secures our presence here, / and I can't seem to say a damn thing".

There's no such reticence in the three-part title poem that forms the book's core. It wittily dramatises an analysis session between a garrulous client  who seems to glean no end of insights into his neuroses through myth, literature and history  and a shrink who struggles to follow him, always trying to bring him back to the prosaic present. If the poem's organising metaphor  the flow of water as a symbol of passing time, of what comes down to us from the past, as well as an elemental life-force  perhaps feels a little forced, it doesn't detract from the self-mocking humour that animates it.

That humour, one senses, is a necessary defence against the awareness that, "whether looked at from this or the far side of fences, / the grass is basically ashes, / and that half-full or -empty, the best-laid glass / invariably smashes". In this poem ("To a Pessimist"), the gloom is also counterbalanced by a rare through-burst of something like gratitude for the world: "To be born, to have hollowed / this singular passage, the exact / outline of yourself, through the rock of ages, / argues, does it not, that one might be allowed / if not to aspire / to outright happiness, then at least to resist / abject despair?" It is, admittedly, a grudging comfort, a pessimist's optimism that's available only to a retrospective view, but it's the best we're going to get in the face of mortality.

Something similar is going on in the finest poem here, "Blueberries", which collapses time by having the speaker, planting fruit bushes in his garden, address himself 20 years on, warning himself not to "go soft" and put any faith in the hereafter: "since the only certain / eternity's the one that stretches backward, / look for it here inside this garden /  / This was your labour, these are the fruits thereof. / Fill up your bowl old man and bring them in."