We've all seen it at least once in our lives, though few of us are ever fully conscious of it. That peculiar moment when, seemingly without cause, the world gets a little bit brighter, communities come together, and new friends are made. The story I'm about to tell you is neither exceptional nor out of place. However, it was the first time I was cognitively aware of this phenomenon while it was happening.

A typical Monday afternoon, the regular routine of cleaning up the house and grocery shopping to prepare for my 4 days with my child. The day had been so chilly, then finally warmed as I was headed out to my car. Windows down and music blasting from the stereo, I went about my business.

Arriving at the store, I hadn't noticed anything peculiar. Everyone seemed to be minding their own business and keeping to themselves. As I perused the produce section, I noticed something different. A man walking by was humming. I hadn't recognized it at first. It wasn't until the second person started humming the same song that the words started forming in my mind. Then the third person.

Before I knew it I was singing it softly while browsing for my groceries, and across the store, I could hear others humming it as well. I watched the tune jump from person to person, a song so simple and so common place that everyone knew the words to it. The tune infected each person like a virus and seemed to almost lift a weight off their shoulders. I watched, casually noting the effects, and completed my shopping.

Waiting in line at the only open check out line, a woman pulled up behind me with her cart. She seemed to have maybe 12 things, and because I had a full cart, I offered to let her go first. The stress over time I had experienced before the hum had completely left me, though I wouldn't be conscious of that until later. I had all the time in the world, I felt.

So when two young women jumped in line behind me carrying a handful of groceries, I offered to let them ahead as well. They seemed thankful; given the weight of their items, I was happy to wait. Especially since my OCD makes putting items on the belt take longer than the usual person. It seemed pleasant, but this is when things started to get a bit different.

A man in a wheel chair rolled up with all of one item and was trying to navigate past the bodies and carts to get to the end of the line 7 people deep. The first woman I had let go ahead of me stopped him and asked him if he'd like to go before us; he asked if she was sure, and not only did she nod, but as I looked around I saw everyone in line nodding their agreement. I found even I was nodding and smiling. That wasn't the part of things that were different by the way.

As I looked around, people started talking to each other. Everyone in line, talking and laughing and smiling. Commenting on the weather, local events and the store itself (which had recently been renovated). As I left the pattern continued. People who were done with their carts (which are coin operated) started handing them off to incoming customers and refusing to trade for the quarter they had put in the cart. Instead, one woman said to just "pay it forward" with a smile, and left.

Everyone wore a smile, for seemingly no reason, and it all started with a hum.

For the life of me, I can't even remember what song it was.