This is probably the most famous line of poetry by Gertrude Stein, written in 1913. In my research I learned that there have been many parodies of this line. Here are a few of my favorites:
The sentence was parodied by Ernest Hemingway after a brief time in Paris seeking editorial suggestions for his writing: "a stone is a stein is a rock is a boulder is a pebble."
It also appears in his 1940 novel For Whom the Bell Tolls, in which there is yet another parody: "a rose is a rose is an onion."
In the 1952 musical film Singin' in the Rain, in the musical number "Moses Supposes." While parodying a dialogue coach, the characters of Don Lockwood and Cosmo Brown sing: "...A Rose is a rose is a rose is a rose is / A rose is what Moses supposes his toes is / Couldn't be a lily or a daphi daphi dilli / It's gotta be a rose cuz it rhymes with mose!"
I'll bet you could think of others.
Lovely prose.