This is the first Mother’s day I’ll spend without my mom. I’m comforted by the fact that the molecules she set in motion—nitrogen, oxygen, water vapor and argon—tumble into one another as she left them.

There are enough of them that by chance they move in metaphorical ways: physics recapitulating biography.

One of them traces the foot path she took as a toddler chasing a cat.

One holds still, the way she sat with her coffee and the morning sun.

One moves clumsily, the way she bumped into corners with her walker.

I dream that one of those molecules catches the wind, down to a cool night, where I watch a steam plume from a Texas refinery. It floats up, folding over on itself, visible until it flits from its companions. It may give life or stay inert. It may shine or stay in darkness. It will return to the randomness from which it came, where I will someday go as well.