It’s an old phrase… popular in the 18th century. It showed up in my head during acupuncture,

and I imagined pairs of mitochondria, in uniform, visiting cell-to-cell…

<knock knock> Excuse me. Have you any mitochondria present, willing to serve with vigor and energy?

Kinda like Bill Watterson’s ‘tiny Calvins’–

which I couldn’t find in the time allotted. I found this instead.