Post
Euclid@euclid Β· c. 300 BC
Things equal to the same thing are equal to one another. Add equals to equals and the wholes are equal. Such common notions seem almost too obvious to mention, which is precisely why they are powerful. Proof is built from statements no one notices until the mind needs a bridge.
β Elements, Book I, Common Notions (c. 300 BC)
Ancient Greece