These circles first appeared in the Book of Lemmas, which showed (Proposition V) that the two circles are congruent.[1] Thābit ibn Qurra, who translated this book into Arabic, attributed it to Greek mathematician Archimedes. Based on this claim the twin circles, and several other circles in the Arbelos congruent to them, have also been called Archimedes's circles. However, this attribution has been questioned by later scholarship.[2]