Even in the colossal threshing barn, the first room we enter in Hauser & Wirth's year-old gallery in Bruton, Somerset, Jenny Holzer's new 2.5m LED ticker Move is a commanding presence, able to stand on its own. Or rather hang, vertically; its text rising up to the vaulted ceiling in a rhythm controlled, via sensors, by the movements of visitors.

It's mesmerising, not least because its 'thoughts' are extracted from wartime documents declassified by the US government in response to Freedom of Information requests. To read Move in its entirety would take most of the day, but even ten minutes will get you in the gut. It is the flagship installation in a mini-retrospective that encompasses her Truisms of the 1970s and 80s; her 1994 Lustmord Table from the height of conflict in the former Yugoslavia; and new paintings that faithfully and painfully transcribe declassified documents.

Holzer's work speaks volumes, to twist the cliche. So loaded is it with the power to bewilder and infuriate, it is, perhaps, unsurprising that the artist herself would offer so few words as commentary. What more could she have to say?

Present and amenable at the recent launch of 'Softer Targets', Holzer nonetheless spoke sparingly. Her positioning of Move, dangling downward at the centre of the 18th-century barn, was 'possibly Freudian'. As we proceed to the next gallery, lit naturally from unusually tall windows, she expands on how useful it was to handle the primary source material, gathered over weeks at the National Archives in Washington DC.

'These documents were written in the moment, by people who were not thinking anyone might be reading it one day,' says Holzer. 'It's not just one person's filter – they were reacting to orders and decisions made by others.'

Here are the new paintings, hand-traced from victims' own script, testimonials of 'very sad and very brave things'. One is taken from a woman clearly suffering from mental illness, another from an Afghan prisoner whose brother died in custody. An earlier series reproduces heavily redacted memos – one of which leaves just a single word uncensored: 'waterboard'. 'You wonder if the people tasked with redacting the text were playing around,' says Holzer. If 'waterboard' was the least damning word in the memo, what's been blacked out? Or was leaving it exposing a red herring?

In the Rhoades Gallery, a 12m LED post called Floor butts up against the wall, its cascade of text – extracts from the artist's best known works – seemingly sucked into and spat out by the adjacent wall. It directs us outside, where one-line Truisms from Holzer's early career are carved into a collection of granite benches. 'As a child I thought the art world would be much improved if there was just more seating,' says Holzer.

Nearby, Louise Bourgeois' Spider perches in the full summer grass, leading the eye to the big sky, providing solace. Out here, the inevitable lump in the throat begins to ease. Feelings of peace and freedom pervade the country air. 'It's kind of great having the spider on guard,' says Holzer.

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