Euclid's Elements is a hoax! You can tell because the proofs all end with "QED", but that's Latin, which hadn't been invented yet.
THEY HAVE PLAYED US FOR ABSOLUTE FOOLS.
@mjd Obviously the argument falls apart if one is looking at an English translation of Euclid because neither English nor Latin were popular languages then. (The oldest known Ancient Latin inscriptions predate Euclid's elements by a few hundred years.) Going down to the Bodleian we can read a Greek text copied in 888 AD were propositions end with the text (Prop 7 from Book I) ὅπερ ἔδει δεῖξαι corresponding to Q.E.D. (quod erat demonstrandum) or (Prop 10) ὅπερ ἔδει ποιῆσαι which corresponds to Q.E.F. (quod erat faciendum) because Prop 10 is a construction.
https://www.claymath.org/library/historical/euclid/files/elem.1.10.html