A perfect parable for ageing, from a film starring Mr Potato Head

PRESENT TENSE:IF YOU DON'T have a kid with an extensive DVD collection, you may not have seen Toy Story 2for some time. Before Toy Story 3is released, in a week, you should try to watch this instalment again.

It’s a wonderful film, endlessly watchable. You’ll laugh. You’ll cry. You’ll be paralysed with existential pain brought on by the fear of ageing and abandonment by those closest to you.

There are tough moments – Wheezy the penguin being found on a dusty shelf; Woody’s nightmare about life after his owner grows up. But there is a particularly affecting montage that condenses into a minute the lifespan of Jessie the cowgirl, from constant companion of a young girl to an unwanted symbol of immaturity and, ultimately, into a charity box.

The film ends with her and Woody side by side, facing that inevitability together, determined to enjoy the good times while they last, but not before Jessie displays some serious emotional scarring as a result of her experience. As a parable for ageing and death it far exceeds anything you could have hoped for from a film with Mr Potato Head as a lead character.

That montage was about as heartwrenching as anything Pixar did until Up, which delivered one of cinema's genuinely great moments with a wordless montage tracing the childless marriage of Carl and Ellie, as their dreams are repeatedly bumped aside by the practicalities of life. It collapsed the cruelty of time into a devastating sequence that had parents blubbing in their seats while their kids bounced about in a rain of popcorn, oblivious to our mortality.

Pixar, though, specialises in making animated films that are not only brilliant on the level they should be – as artistically accomplished entertainment for everyone – but are also profound on a level we shouldn’t expect. And it has done it repeatedly.

Upwas interested in an old man's isolation and grief. The opening 15 minutes of Wall-Ewere a mute sequence of post-apocalyptic slapstick and loneliness that moved animation forward by drawing on the soul of early cinema.

Finding Nemowas an adventure about a little fish trying to get home, but it was also about parenting and the fear of child abduction. In keeping with Pixar's early injections of throat-tightening emotion, and matching Bambi's troubles and then some, Nemo's mother and all his prospective siblings are slaughtered early on. It establishes an understandable paranoia in Nemo's father that propels the entire plot.

As for Cars, it wasn't great, so let's not dwell on that one.

In the US they've been lucky enough to have Toy Story 3in the cinemas for weeks already. Its box-office performance has matched the rhapsodic reviews, and it now stakes a claim for being among the most complete trilogies. Its audience, though, are not families: it couldn't have had its strongest ever opening if it was. It is also grown-ups who have long abandoned their toys.

Generously offering a neat comparison, the Shrekmovies have shown just how easy it is for a big-studio, big-voiced animated series to descend fairly effectively into self-reverential laziness, nothing but a cartoon that happens to come with the merchandising.

Pixar has largely avoided sequels, seemingly content to complete a story in as solid a way as it can and allow the audience to write its own futures. A sequel to Carsis on the way, apparently, but so far only Toy Storyhas played out past the first movie.

There was some question about the necessity for a third instalment, but it has taken the themes of Toy Story 2and found new life in them, with the New York Timessaying it "raises provocative questions about a fittingly topical subject: the greying of the American population in 2010".

In Toy Story 3the whole cast has experienced Jessie's trauma, now unwanted by Andy, who has gone to college. They wind up in a creche that mirrors retirement homes – even down to its name, Sunnyside. Again, the New York Times: "Disillusionment awaits our protagonists, as it usually does in portrayals of late life made in a culture fearful of age, and, with its toy bins like prison cells, Sunnyside slyly revises Dickensian tropes about institutional care as incarceration."

The series represents the circle of life. The first movie features Buzz Lightyear’s arrival in the world and the threat perceived by Woody, an established toy. The second is Woody’s midlife crisis. The third deals in the inevitability of growing old. “To infinity and beyond” has come to have a very different resonance.