Pappus's Hexagon Theorem/Historical Note

Historical Note on Pappus's Hexagon Theorem
Pappus's Hexagon Theorem was first proved by in about $300$ CE.

The theorem is stated as Propositions $138$, $139$, $141$, and $143$ of Book $\text{VII}$ of 's.

In $1899$ its full significance was revealed by, during his work on clarifying the foundations of geometry.