“Fidelio” (Leonore, or The Triumph of Married Love, Op. 72) is Ludwig van Beethoven’s only opera.
The setting is a political prison near Seville in the 18th century. The opera tells how the courageous Leonore, disguised as a prison guard named “Fidelio” searches for her husband Florestan who is wrongly imprisoned for his political beliefs. When Florestan’s execution is imminent, “Fidelio” risks discovery and death for love, finally freeing her beloved from his chains and his fellow prisoners from oppression.

The pattern of the socks shows vertical lines like the prison bars in the opera, but if you look more closely you’ll see them forming X and O s , representing the final triumph of love over tyranny.

A more delicate, feminine version of this pattern can be found here: Leonore

ERRATUM: the RS row of the heel flap should start with a sl yb instead of yf, i.e. this is how it’s supposed to read:
RS: sl yb, k1, k2, p2 7 times, k4, turn