Inside Out is still Pixar's best ever movie

This week, cinemagoers will get the chance to delve back into the mind of Riley with the release of Inside Out 2. It has taken Pixar nine years, but they're finally following up on the movie that showed they still had the mojo when it comes to original storytelling.

In fact, Inside Out is even more special than that. Even in the high-quality ranks of the Pixar canon, the movie stands tall. It's the best thing the studio has ever made.

Inside Out, like many of Pixar's best ideas, came from the brain of Pete Docter. By that stage, he already had Monsters Inc. and Up under his belt as a director, having also contributed heavily to the stories for the first two Toy Story movies. These days, he's chief creative officer at Pixar, with a huge role overseeing all of their movies.

But in 2009, he had finished work on Up and noticed that his daughter Elie was becoming quieter and less outgoing. This inspired the idea that, by the end of that year, was an active project in development at Pixar. It took six years for Inside Out to make it from that original concept to the big screen.

Read more: Pixar's Pete Docter shares theory on why Toy Story spin-off flopped (Yahoo Entertainment)

One of the reasons the finished film is so immaculate is that Docter and the rest of the Pixar Brain Trust took their time and took the material seriously. As well as drawing from personal experience, they consulted with child psychologists and neuroscientists.

Their goal was to create a detailed and complex depiction of how a young girl's brain works. Through the prism of five emotions and the combinations between them, Inside Out is a sensitive and nuanced exploration of how life changes can affect young people.

The central concepts are thought through with real intelligence, from the "islands of personality" that are created by "core memories" to the way those core memories can be tinged with other emotions in later life. Personalities are formed by emotional experiences, whether happy, sad, or something else.

The movie begins with Joy (Amy Poehler) and Sadness (Phyllis Smith) as diametrically opposed characters who cannot co-exist. In fact, Joy doesn't even understand why Sadness has to be there. As a child, you're governed by joy and tend to seek it out above all else. But an older child requires the intermingling and maturing of emotions, with joy sometimes forced to take a back seat.

Read more: Inside Out 2 takes unexpected inspiration from an Adam Sandler movie (Digital Spy)

It's a brave message to convey to a young audience of cinemagoers — the idea that sadness has a serious and vital role in our lives. That's not to mention the chilling moment in which Riley's mind console is switched off, leaving her blank and emotionless in the sort of way we've all felt at times in our lives. The genius of Inside Out is in finding a fantastical explanation for the most real feelings.

And that's before we even start to talk about Bing Bong. The ability to tug violently at our heartstrings has been a Pixar hallmark ever since the studio's earliest days. But there was something weapons-grade powerful about the way in which Bing Bong took the notion of an imaginary friend and made it an existential nightmare.

There's something very bleak, but also comforting, about the idea that our childhood acts of mental escapism are still there, just waiting for us to need them again. Unless, of course, we don't need them and they are forgotten forever, fading away to dust like Thanos has been snapping his fingers again.

Almost a decade later, I'm still incapable of even thinking about the words "take her to the moon for me" without tearing up.

Inside Out is the high watermark of the Pixar formula, marrying colourful characters and kinetic adventure with very human concepts. And it's not as simplistic as saying that the emotional elements are there for parents while kids are distracted by the bright colours. The reason the movie works as well as it does is because even its most sophisticated elements are accessible to all generations.

Read more: Every Pixar film ranked from worst to best according to fans (Yahoo Entertainment)

The sequel certainly has a lot to live up to. This time around, Inside Out co-writer Meg LeFauve has been joined on scripting duties by Kelsey Mann — a storyboard artist who is also making his directorial debut with the film.

Watch: Trailer for Inside Out 2

On the face of it, there are some big changes. There are a handful of new emotions in the film, including Anxiety and Envy. These reflect Riley's increasing maturity now she's in her teenage years, but also risk complicating the structure of the mind's headquarters a little too much. The first time around, it made sense for the core emotions to mix like primary colours in order to create more nuanced feelings. This time, though, they're getting their own physical embodiment.

Nonetheless, Pixar has earned our trust in a big way over the last 30 years of storytelling. And never more so than with Inside Out — one of the most sophisticated and beautiful animated movies ever made.

Inside Out 2 is in UK and US cinemas now.