Huh? OK, look at the title again. The two sentences follow because they’re connected by association rather than logic; the words ‘flies’ and ‘like’ use the same letters on both occasions they’re used, but have different meanings, yeah? But they’re enough to tie the sentences together into something that would be funny if I hadn’t spent this paragraph deconstructing it.

All of which is to make a point, itself concerning time. As writers, we can construct stories that work in a linear fashion, or otherwise. That is, we can have scenes which follow one another in the sequence they actually happen, or in another sequence. The thing being, how do you know which option to choose?

A few years back, scatterbrain that I was, I tended to the structurally complex. As I learned more about writing and structure, I realised that this was because I wasn’t truly in command of my material, and was being tricksy — that is linking sequences through clever rather than felt connections. Problem being, that’s not how most people work most of the time, and there’s a danger of losing audiences that way. Audiences, by the way, is a category that includes script readers and producers.

So, how do you really know when a non-linear approach is best, and not just a clever gimmick masking your lack of control of your material? Some clues came up in a couple of films I’ve watched on DVD recently. Before The Devil Knows You’re Dead is written by Kelly Masterson and directed by Sidney Lumet, and tells the story of a robbery planned by two brothers on their parents’ jewellery store. The story weaves in and out of the present moment, going back to explore aspects of what went on in more detail. Hard Eight, an early film by writer-director Paul Thomas Anderson, is the tale of an ageing crook who takes a loser under his wing and comes to work with him, and also utilises some non-linear elements as part of the narrative.

Before The Devil Knows You’re Dead is much the more successful film, and that’s because the writer and director know just what they’re doing and why. Each choice to go back in time is done as the natural consequence of the emotions one of the characters is feeling, and which are explained in more detail by the flashback that follows. In Hard Eight, the decisions to go back into the past are seemingly random, to bring to visual life a relatively arbitrary detail of the plot so that it’s seen as well as referred to. The lesson here seems to be that ’show don’t tell’ isn’t always the best way to do things on-screen.

What lessons can be learned from the way these two films approach flashbacks? Primarily, that going back in time works best when it is triggered by emotions. As such, that reflects the way that people think, by association. You see someone who reminds you of an ex, and then dwell on that ex for a while, for good or ill. The more illustrative method used in Hard Eight might work on paper, but since the flashbacks are not truly motivated they lack power in practice. That said, the film did demonstrate one valid way of camouflaging a flashback , in this case to illuminate something about the old man at the centre of the story, who watches a video of his protege getting married. The video was in effect a flashback in disguise, and that’s a good way of demonstrating how associative processes can work without using the device of a formal flashback.

There are other ways to use non-linear structures too, as with Pulp Fiction for instance. The danger being, the more a story draws attention to the methods of its construction, the less involved an audience will be in that story. Which kind of works for the hip referentiality that Tarantino traffics in, but can mean a lack of emotional affect. One glorious exception to this is the delightful Eternal Sunshine of the Spotless Mind, which has a labyrinthine construction but is guided throughout by the theme of love recollected.