On an overseas holiday with my family, I proved myself a coward. I stood by and did nothing because doing something would not have been easy - it would have been uncomfortable and worst case scenario, it could have put me in a dangerous situation.
Inside a sprawling park in Bali - a park that sells itself as "family fun'' - I watched a father strike his son's head.
Whether he struck him with a closed fist or an open palm I have no idea, but the hit was loud enough that I heard it from about 20 metres away while holding a yammering two-year-old.
The son was a teenager, taller than his dad, and barely reacted to the knock.
Maybe the impact was somehow loud yet gentle. But I doubt it. I suspect the son is used to copping knocks upside the head and now shrugs it off. It was also loud and violent enough that a middle-aged Balinese staffer confronted the man to say there was no fighting allowed in the park.
A woman with them rushed to calm the situation.
"Oh no, you don't understand," she told the bewildered worker. "It's just our son."
The staffer looked more confused.
Then he walked away, giving me a look to say, "Can you believe that?"
He might have thought this was an Australian thing.
I don't know why the dad hit the boy. I don't know if the son had whispered something unspeakably cruel that forced his father to react in violence.
I don't want to judge other dads. I'd say that every day you keep everyone fed, happy and together is a victory. But this was not a child in harm's way. This was an almost adult standing beside his father, struck by the man in public. The son didn't react.
And as the family walked off to spend the rest of their day at the park, my stomach churned.
I'm a grown man. I have a child myself. I have friends who know the sting of parental abuse.
I stand up for them, and I should have stood up for that boy.
Instead of standing strong like the man I want to be, I wilted like the coward I am.
I hope that son is braver than I was that day. He may need all the strength he has.
Owen Jacques is an award-winning News Corp journalist. Follow him on Facebook or @Owenjay on Twitter.