Songfacts®:

• "Lux Æterna" (or "Lux Aeterna" typed in the Western alphabet) is Latin for "eternal light" and part of the Catholic requiem mass. This song is an old-school sounding rocker in which vocalist James Hetfield touches on humanity's shared need for salvation.
• Hetfield uses the title phrase as a rallying cry for humanity to unite against the dark forces destroying our planet.
  
  A sea of hearts beat as one, unified
  Magnification
  All generations
  Approaching thunder awaiting the light
  
  As the human race comes together as one, we become a light that guides the way and dispels the darkness.
• In the second verse Hetfield tells of the cathartic powers of rock music bringing the light into our existence.
  
  Commiseration
  Sonic salvation
  Cast out the demons that strangle your life
  
  Hetfield has had a lot of darkness in his life, but he's learned to focus on the good things to bring balance. "Everyone has some sense of hope or light in their life, and, obviously music is mine," he said in a behind-the-scenes look at the making of 72 Seasons. "And the song specifically talks about gathering of people at a concert and [being] able to see the joy and the life and the love that comes out of music and the family and the kinship in that, and just a sense of uplifting."
• Hetfield nods to a couple of other songs to get his point across.
  
  We need to act quickly before its too late
  Full speed or nothing
  
  The Metallica frontman is borrowing a lyric from "Motorbreath," from the band's 1983 debut album Kill 'Em All. That song is about people who prefer to sit and accomplish nothing, rather than taking chances in life.
  
  Amplification
  Lightning the nation
  Never alive more than right here tonight
  
  "Lightning to the Nations" is the title track of Diamond Head's 1980 debut album. Metallica acknowledges the English heavy metal band as an important early influence and has frequently covered their songs in their concerts.
• Hetfield co-wrote "Lux Æterna" with his bandmate, Lars Ulrich. The Metallica vocalist and drummer are the band's main songwriters.
• Metallica released "Lux Æterna" on November 28, 2022, as the lead single from 72 Seasons. Hetfield and Ulrich co-produced the album Greg Fidelman, who engineered and mixed their previous record, Death Magnetic.
• Tim Saccenti filmed the performance video in Los Angeles on November 3, 2022. Saccenti has also shot visuals for Depeche Mode and Korn.
• Metallica performed "Lux Æterna" live for the first time on December 16, 2022 at the band's Helping Hands Concert & Auction, which took place at the Microsoft Theater in Los Angeles.