De aeternitate mundi, contra murmurantes

De aeternitate mundi, contra murmurantes (lit.'On the eternity of the world, against the murmurers') is a treatise by the Doctor of the Catholic Church Saint Thomas Aquinas regarding the possibility of an ever-existing universe.

The work is usually dated around 1270 and is particularly brief. Aquinas uses the medieval definition of world, which refers to "the totality of creatures". Despite acknowledging the denial of an eternal universe by Catholic doctrine, the saint attempts to study the logical coherence of such a proposition from a philosophical point of view.