I was reading Barthes' The Grain of the Voice, the only good take on ineffability and je ne sais quoi in art, when I came across this line (emphasis mine):
How many singing teachers have we not heard prophesying that the art of vocal music rested entirely on the mastery, the correct discipline of breathing! The breath is the pneuma, the soul swelling of breaking... The lung, a stupid organ (lights for cats!), swells but gets no erection...
"The lung, a stupid organ (lights for cats!)"
I fell in love with the phrase on sight. The perfect iambic pentameter, the vowel motion, the sheer contrarianism, the way the text doesn't seem to realize that we've stopped talking about lungs-- it's all there. Of course, it wasn't clear what it meant. "Lights for cats" seemed at first glance to represent the frivolity of a cat chasing a laser pointer-- but Barthes was writing in the 1960s, so that seemed anachronistic.
Long story short, "lights" archaically refers to "lungs" (although Merriam-Webster and Chambers have no clue), as a reference to their lightness qua weightlessness. "Lights for cats" translates a French idiom referring to lungs as low-quality offal that a butcher might toss out to sate the alley cats.
I'm tickled by the innate multiplicity of the phrase-- particularly the word "light", and how its many senses are often funny to imagine discarding to feed an animal. (A butcher plucking out the élan vital of a pig, scoffing, and unceremoniously tossing it out the window.) That multiplicity is central in my poetics, and cats are central to my online identity, and I've been walking around the house saying this phrase over and over for the past few days.