Definition:Euclidean Relation/Source of Name

Source of Name of Euclidean Relation

The concept of a Euclidean relation was named for Euclid.

It derives ultimately from the first of Euclid's common notions.

In the words of Euclid:

Things which are equal to the same thing are also equal to each other.

(The Elements: Book $\text{I}$: Common Notions: Common Notion $1$)

However, Euclid did not delve deeply into the field of relation theory.

The concept of equivalence relations was a much later development.