'The only thing that is constant is change' — Heraclitus, Greek philosopher 

Our ability to change defines us.

Star Wars worked because Luke Skywalker became something greater than even he believed was possible, because Han Solo went from heartless smuggler to selfless soldier. Humphrey Bogart had to transform into a freedom fighter forCasablanca to rise above being just another sad war-torn love story.

The brand storytelling hero’s journey begins with a universal truth — but it’s the final step, transformation, that brings us back home.

Step Four – Transformation

This transformation can take multiple forms: A problem is resolved, the main character or circumstances (the emotional hero) are changed, or a new universal truth is revealed. Transformation can also be a call to action or a reminder to refocus or do things in a different way.

In WestJet’s holiday hit 'Christmas Miracle', passengers experienced a twist of fate by receiving personalized gifts at baggage claim, but the transformation played out in their reactions, their disbelief melting into acceptance and what could best be described as joy. You can imagine that those passengers left the airport a little less cynical and a little more hopeful about humanity.

As the 'hero' transforms, so does the audience. Unilever’s Project Sunlight begins with a simple yet powerful question: 'Why bring a child into the world?' A global cross-section of expectant parents shares its concerns and fears, sometimes adopting an almost defeatist tone.

But then they see pictures of what the future might hold, that their children have a better chance of living longer, living better than we ever did. The transformation is complete when one of the soon-to-be dads says, 'How the story pans out depends on how we behave in the story.'

The parents transformed their fear of bringing a child into the world to anticipation and a call to action for others to get involved and create a better future for all children. As an audience, we are transformed and encouraged to transform others.

This is the best kind of storytelling, the kind that makes a difference. It’s a story with staying power and lasting impact. It’s a story that reminds us that we have the power to change.

Transformation makes us, and our stories, more human.

Gary Goldhammer is Hill+Knowlton Strategies' US digital strategist.