Not only David Lynch's first film but arguably his definitive one. Despite going a little bit more commercial with Dune (which he virtually disowned, admitting studio interference ruined it) and being asked to direct Return of the Jedi (imagine that version!), it heralded the arrival of a director who effortlessly captured aesthetics from avant garde to just plain weird.

Ironically, the reasons for the weirdness in Eraserhead are comparatively simple considering the rest of his oeuvre – I found later films like Inland Empire impossible to get a grip on entirely.

First, neither you nor the protagonist Henry (Jack Nance) really know when he's in the real world or when he's dreaming. Maybe the whole thing's a dream – among dozens of others Lynch influenced, did Chris Nolan give him a nod with the deep central mystery of Inception?

Second is the evocatively weird location. The story is situated in a nightmarish world in the shadow of a clanking industrial landscape where nothing grows properly despite the driving rain and awful weather, where there's no sky or horizon and everything's perpetually shrouded in darkness.

The film as a whole is a fairly obvious metaphor for fear of parenthood, both of the catastrophic change having kids makes in your life and how little protection you can really offer them in the world of matter and flesh.

Henry and girlfriend Mary's (Charlotte Stewart) baby is a literal alien or monster, and every new parent can relate to the infant-as-constantly-demanding-parasite parable, a creature who may or may not be sated no matter how hard you try.

It's such a universal (and slightly unspoken) theme it's been alluded to in art and movies from Rosemary's Baby to We Need to Talk About Kevin and Prevenge, and they're only some of the modern expressions of mythologies that go back to Prometheus and Oedipus, of our creations turning on us.

We start with bizarre images of a guy's worried-looking face superimposed over what seems to be a planet wheeling around in space, the man spewing out a creature that looks like a giant sperm. It fades to a guy manipulating old-style railway switch levers in a room blazing with monochrome contrast, then we cut to the first guy, Henry, walking home through what looks like the staging yard of an abandoned manufacturing plant.

As we learn later, he's a printer. He lives in a drab little flat that's as dingy as the world outside – take notice that there isn't a potted plant on the beside table but a pile of dirt with a bare stick sprouting a few sad-looking leaves.

As he arrives home, the sultry women who lives across the hall from Henry tells him girlfriend Mary, who lives nearby, has invited him for dinner. Henry duly attends, enduring an increasingly awkward visit thanks to Mary's preternaturally cheery father and guarded, suspicious mother who tells him he has to marry Mary because she's pregnant, then tries to force herself on him.

Mary has the monstrous baby and moves into Henry's place, but its constant low wailing drives her insane from lack of sleep and she quickly moves back to her parents, leaving him to take care of it. When he attempts to do so, the nightmare begins.

The baby develops sores all over its body. Henry peers behind his radiator to find it opens up, revealing a miniature stageshow set where a showgirl sings a bizarre song, stomping on multiple copies of the sperm-like creature we've already seen.

He sleeps with the sultry woman across the hall, then has a fit of jealousy later when he sees her in the arms of another man. His head falls off, replaced by that of the monster baby. A kid from the neighbourhood finds his head in the street and takes it to a pair of guys who appear to be mobsters but work at the factory who then take it and turn it into pencil erasers.

If that's not weird enough for you, Henry unwraps the baby's swaddling to find it doesn't have any skin, just a loose clump of organs. When he attacks it with scissors it grows to gigantic size, filling the apartment. We visually refer back to the planet spinning in the void from the beginning, the lady in the radiator makes another appearance and it all disappears in a flash of light.

Has it been a dream since Mary left? Was it the whole time? Does it matter, when Lynch never explained himself that fully (even he might not have known) and film fans are still reinterpreting it almost 50 years later as I write these words?

It's obvious – and has been across his career – that Lynch wrote and directed by feel, not by what made sense, so just like 2001: A Space Odyssey, we might be trying to figure it out forever.

I expected to be scratching my head almost the entire time (and did), but the real surprise was how much full-on body horror it contained, from the miniature chickens during the dinner sequence to the unswaddling of the baby.

As well as being the Grand Poobah of weird, Lynch was also the figurehead of the DIY movement that later eras and digital technology would enable. Back in 1977 such an approach to making movies was barely even known, let alone named, and the only real progenitor it might have had was the career of Ed Wood.

But Lynch wrote, directed, produced, edited and designed over years when scheduling and budgeting allowed bringing his story to life by brute force.

You'd have to be a Lynch devotee to convincingly use the word 'enjoy' to describe your reaction to Eraserhead (I'm not) but it stands tall among the cinematic pantheon and even though I'll likely never watch it again, I can't call myself a cinephile without having seen it.