Fifty years ago this month, The Beatles released their sixth UK album ‘Rubber Soul’. The album offered the first true glimpse of John, Paul, George and Ringo moving away from the R&B songs that had kickstarted their career three years earlier and embracing the kind of beliefs and influences that would change the face of popular music forever. Stick it on in full now, play it extra loud and read NME’s Emily Mackay’s argument for why it’s the best Beatles album of all below.

You can make too much out of a title. It’s unlikely anyone pondered long over the words ‘With The Beatles’. This, though, being the first album sleeve on which this by-now hyper-iconic band chose not to bother putting their name on perhaps justifies placing more than usual significance on those words: ‘Rubber Soul’. Lifted by McCartney from ‘plastic soul’, a description he’d heard of Mick Jagger’s singing style, the pun succinctly encompasses The Beatles’ self-deprecating, sceptical humour, their growing unease with their constructed nature as a pop act. Most importantly, though, it suggests a willingness to push the plasticity of their sound, to see how far they could stretch their accomplished pop expertise in unexpected ways before it would snap back on them.

A confused, sometimes uncomfortable threshold between perky, prize-fighter pop and the point where they started writing their own rules, ‘Rubber Soul’ is engaging for just that reason: it’s an album that constantly sounds like it’s trying to find itself. Here, the lovable teen mag moptop mask slips, and the ugly emotional truths of sex and sentience in the mid-‘60s are suddenly disrobed. A multiplicity of influences comes into play, leading to disparate and disorientating ride, indebted variously to Elvis, Otis Redding, Motown, The Byrds and Bob Dylan, but never in thrall to anything but the band’s own need to break free.

And yet, rather than the rush of creative discovery, the emotional tone of the album is irritable, confused. The exuberant vision of a world of sharply dressed, bright-eyed young things is swapped for the more frustrating, fractious women (‘You Won’t See Me’, ‘Girl’), failed one-night stands – ‘Norwegian Wood (This Bird Has Flown)’, ‘If I Needed Someone’) – and satires on superficial scene girls (‘Drive My Car’).

‘Norwegian Wood’ in particular marks the moment The Beatles stopped settling for craft and took a shot for art. It remains one of the most weirdly, quietly enchanting songs in their canon, it s mystical elegance interacting oddly with the deconstruction of sexual liberation – boy meets girl, boy doesn’t get any, boy burns girl’s furniture in revenge. Nasty, funny, beautiful.

This strangely modern, English, sceptical way of deconstructing the hippy free-love dream before it had even really begun is shared by George Harrison’s acerbic, thickly harmonised, fuzz-bassed ‘Think For Yourself’, whose assertion of independent-mindedness prefigures Lennon’s ‘Revolution’.

It’s not all venom and negativity, of course: ‘The Word’ anticipates the birth of Haight-Ashbury idealism, but the real politics of ‘Rubber Soul’ is personal, the real harmony, if there is any, to be found on an individual level. The late highpoint of Lennon’s ‘Girl’ is a weirdly beautiful, dissipated, country-folk thing. His nakedly elegiac ‘In My Life’, with its gently melancholic musings on the transience of childhood memories, is a subtle glory.

In contrast, the relative inanity of McCartney’s ‘Michelle’, more in keeping with the rose-tinted pop simplicity of earlier days, is balanced by the cool gorgeousness of the chanson-style melody, the barber-shop ‘oooh’s, the delicate summer-evening fingerpicking, and offset by his rough-edged, lusty cry of “I want you, I want you, I want you”.

‘What Goes On’, on the other hand, feels slapdash, makeweight: an older song resurrected to fill the album out. Also Ringo sings it.

‘Run For Your Life’ might cause winces to the modern listener; few male songwriters today would consider writing lyrics threatening their girlfriend with murder if she’s caught cheating. You could qualify that distaste by pointing out that in the blues tradition, of which both Lennon and Elvis, from who he stole the opening line, were devotees, boasts much more graphic threats of crime passionnel.

For all its frustrations, ‘Rubber Soul’ remains the most satisfying listen in The Beatles’ canon: full of variety, full of struggle. At its best, there’s a perfect balance between tradition and experimentation, a sweetly sugared pill rather than the forced ECT of ‘Sgt Pepper’. The rubber might snap back and hit you in the face sometimes, but it doesn’t mean you should stop stretching.

This article originally appeared in NME’s Beatles collectors’ issue, published on 12 September 2009