A five-year-old girl, wildly happy to be on South Beach with her mom and dad on a sparkling summer afternoon, chases her shadow down the strand. Suddenly her screams shatter the tranquility. She crumbles to the sand, terrified at sudden, intense pain. Her parents rush to her aid, wide-eyed and shocked. Penetrating the sole of one tiny foot is a large jagged shard of green glass. In trauma and disbelief, they tear to the hospital, intent only on immediate help for their desperately crying child. Would she ever run carefree down a beach again?

Fast backward a day or two. A small group of friends is enjoying a beach fire. One drink leads to another and another. Most smile as someone impulsively tosses a bottle of vodka into the flames. Another soon follows. Laughter dismisses consequence. As the party moves on to other adventures, some sand is kicked over the fire, burying much of the wood and glass.

I imagine these two scenes last Thursday morning as I draw my fingers slowly through Chilmark sand, searching for every trace of those bottles. I collect 60, maybe 70 pieces of glass, some melted by fire, some the size of my fist, some as small as a needle. A few rusty nails from the burnt wood seem almost harmless by comparison. I am left to ask those responsible, should they read this, for what reason under the sun would anyone, anytime, anywhere leave such a vicious trap for innocent others.

Tony Balis, a resident of Vineyard Haven, is president of humanity.org.