Sometimes it doesn’t take much to start a positive chain reaction. Take this example in a Philadelphia diner where one couple anonymously paid for another table’s bill:

“It was magical. I had tears in my eyes because it never happened before. I’ve been here for 10 years, and I’ve never seen anything like that,” said Lynn Willard, a waitress.

Willard and other waitresses told NBC Philadelphia that the couple started the chain reaction by paying double: for their own meal and for the tab of another table of diners at the restaurant. There’s no evidence that one group of diners knew the others.

“I could not believe it. And it continued and continued — it was very nice,” said Willard. “They asked us not to say anything until they left, say, ‘Merry Christmas, that person picked up your check.’”

For the next five hours, dozens of patrons got into that same holiday spirit and paid the favor forward.

The diner’s manager said not one person was concerned about price of the check — which ran between $12 and $30.

“It was a surprise to all of us; the girls were even taken aback,” said the diner’s manager. “Those who took the check also tipped the waitress. So nobody had to do anything other than pass it on, and that’s what they did. They just passed it forward.”

It’s a true holiday story that proves how a small gesture of kindness can create some magic.