ex rerum natura

Learned borrowing from Latin ex rērum nātūrā (“from the nature of things”).

ex rerum natura (not comparable)

1. From the nature of things; from the nature of the case; from nature; applied to arguments based on observation or experiment, as opposed to pure reason.
   • 1662 Thomas Salusbury, Galileo's Dialogue Concerning the Two Chief World Systems (Dialogue 2):

     Let us hear the Arguments that follow, which are taken, as he saith, ex rerum naturâ.

• in the nature of things