Thus spake Elon Musk on X (someone fetch plz)

Anyway, it's on the US Dollar Bill:

https://en.wikipedia.org/wiki/Novus_ordo_seclorum

"New order of the ages" from Virgil

The mottos were coined by Charles Thomson, the secretary of the Congress of the Confederation.[1][2] Thomson derived the phrase Novus ordo seclorum from a poem by the Roman poet Virgil. He wrote that the phrase signified "the beginning of the New American Era" as of the date of the Declaration of Independence in 1776, which was depicted in Roman numerals at the base of the pyramid on the seal.

So Why did Elon tweet that? Some more on the mythology and symbolism here