 According to Theodore Andrea Cook, Barr gave the golden ratio the name of phi (ϕ).Cook wrote that Barr chose ϕ by analogy to the use of for the ratio of a circle's circumference to its diameter, and because it is the first Greek letter in the name of the ancient sculptor Phidias.Although Martin Gardner later wrote that Phidias was chosen because he was "believed to have used the golden proportion frequently in his sculpture", Barr himself denied this, writing in his paper "Parameters of beauty" that he doubted Phidias used the golden ratio.