ex rerum natura

Etymology
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Adverb

 * 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.
 * 2) * 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.