Anyone who’s spent time with Christian Marclay’s The Clock (2011) will know the feeling. Sitting rapt in the dark, mesmerised by the short snippets of film unfolding, one by one, on screen. The sudden sensation that one has lost track of time, the urge to check the nearest clock. The sheepish, and uncanny, realisation that not only is the exact time currently broadcast on a large screen right in front of you, but you’ve been watching a clock – the clock – this whole time. The Clock’s premise is simple: Marclay spliced together thousands of film clips featuring clocks, combining them into a 24-hour film which is synchronised with the actual time where it is shown, such that the artwork functions as an elaborate timepiece in itself. At 11:46 a.m., we see Christopher Walken deliver an impassioned monologue to a young boy, brandishing a stopped watch that passed through three generations of his family. At 10:04 p.m., we’re in Back to the Future, and lightning strikes the clock tower. Time passes, literally, before your eyes.

In her 1926 lecture ‘Composition as Explanation’, Gertrude Stein described her novel The Making of Americans – written between 1902 and 1912, but not published until 1925 – as ‘almost a thousand pages of a continuous present’. Stein’s epic masterpiece advances not by the development of a narrative, but through rhythms: insistent undulations of repeated words and phrases which attune the reader’s ear (and eye) to the sounds and shapes of her words. Just as time in The Clock proceeds with the subtly perceptible moving of the minute hand, the slight variations in Stein’s cascades of language provide the indication that the novel – and its ideas – is progressing. Stein wanted her work to arrest readers’ attention and hold them in the moment. In The Making of Americans, her long passages of varied repetition serve to block out distractions and induce an almost meditative state in the reader – a state as close as possible to the one in which Stein composed. Later, she compared her composition process to the way the cinema moves forward through a succession of frames, each slightly different from the last. ‘In a cinema picture no two pictures are exactly alike,’ she wrote, ‘as there was in The Making of Americans no repetition.’

The Clock and The Making of Americans are two radical efforts to foreground, formally, the experience of time passing. One is a mammoth stream of prose, constantly spiralling beyond its narrator’s control, the other a film which never ends, forming a 24-hour repeating loop: each work creates structures in which the uncontainable – time – is contained. Neither work presents a past or a future: only what’s currently on the screen, or the page, is real. At its opening, The Making of Americans introduces a cast of characters and the promise of a plot: the novel, Stein announces, will follow three generations of a German-Jewish family as they assimilate into American life. Yet as the novel proceeds, Stein constantly diverts attention away from their stories as she embarks on the quest that defines the novel – to describe every possible kind of human character, thus creating ‘a history of everyone that ever lived’. The Clock, too, sets up expectations of narrative advancement: we’re thrown into the middle of tense situations, and can only speculate (unless we recognise the film) who everyone is and what’s led up to this moment. But Marclay tends to cut away from scenes just as we become invested in them. Timelines merge dizzyingly, as we move from black-and-white Hollywood film to Westerns, shift from the office to the desert in the blink of an eye. Time is the protagonist here: the only constant in what becomes, as the hours pass, a heady portrait of a collective consciousness.

Like Stein’s prose, the rhythms of The Clock are seductive, heightening viewers’ attention to the structures and habits – the repetitions – which govern the average day. As the hour approaches, adrenaline ramps up as people race to catch trains, make appointments, conclude business; as the hand ticks past the hour, there’s a palpable sense of relief as the drama of transition gradually subsides. The hour between 6:00 a.m. and 7:00 a.m. is a cacophony of alarms ringing, of surprised people springing out of bed or blearily reaching to silence the clang. Around 9:00, most people in the film are turning up to work; from 12:00, they start to eat lunch; at 5:00, they leave work; around 7:00 p.m., they eat dinner. (‘There are many kinds of men and many kinds of women and there are many millions made of each kind of them,’ writes Stein.) Quotidian scenes are interspersed, even intercut, with exceptional ones. While one person is putting dinner in the oven, someone else is hanging off a clocktower; heists and murders ensue while, elsewhere, people are casually going about their ordinary affairs. The most important moment in one person’s day, The Clock suggests, will be totally incidental in another’s.

As The Making of Americans goes on, Stein’s efforts to sort humans into character-types morph into an attempt to isolate, too, what makes individuals unique. People reveal themselves, she argues, over sustained, close, long-term observation. A novel about the whole of humanity will also be a study of the individual, just as a film encompassing the whole history of cinema will be composed of distinct scenes, testament to directors’ specific visions. Both The Clock and The Making of Americans are marathon experiences: the novel is 925 pages long, while the film is often shown in 24-hour screenings, with deep sofas placed to encourage viewers to linger. You can, of course, dip and out of them – skim the book, or leave the screening room – but their full effects demand an investment of time and attention. Yet this is precisely because the scale, and the stakes, of their projects are so ambitious. They each set out to offer ‘a history of everyone’ – a portrait of life, in the process of being lived.