Pick a date. Any date. Somewhere in the world, someone is celebrating it. Somewhere else, someone is mourning it. And somewhere else entirely, it’s just a Tuesday. Take November 11th. In France, the United Kingdom, Australia, and Canada, it is Remembrance Day — a solemn commemoration of the armistice that ended World War I at the eleventh hour of the eleventh day of the eleventh month of 1918. Poppies are worn.

Ask any American what happened on September 11, 2001, and the answer comes instantly. Ask what happened on September 12th — or on the many September 11ths before 2001 — and the room goes quiet. Memory is not neutral. The dates we collectively remember are not simply the most important ones. They are the ones that powerful institutions — governments, media, schools — chose to commemorate, teach, and repeat. September 11, 1973: a US-backed coup overthrows Chile’s democratically elected president Salvador Allende.