This poem grabs you by the scruff of the neck from the first line, doesn't it? The primary device is that brutally direct, conversational tone. Larkin isn't using flowery language; it's the diction of a pub rant, which makes the philosophical weight of the sentiment hit even harder. That's the core of it—using coarse, casual language to deliver a bleak, almost cosmic critique. The rhyme scheme (ABAB) is traditional, even nursery-rhyme like, which creates this vicious irony. The form is neat, orderly, and childish, while the content is messy, anarchic, and deeply adult.
Then there's the metaphor of misery and fault being passed down 'like a coastal shelf.' That's the killer image. It's not a chain or a baton; it's a geological inevitability. A shelf is passive, it just exists and accumulates, and the tide of generations merely washes over it, deepening the channels. It suggests something vast, ancient, and utterly beyond individual control. The final stanza shifts to a slightly more resigned, 'wise' tone, but the advice to 'get out' is undercut by everything that came before. The devices all serve one master: to make a fatalistic, anti-romantic idea feel inescapably true through a combination of jarring simplicity and a perfectly chosen central image.