Roman Numerals

In this second novel of the series, Art West seeks out the meaning of the mysterious symbolic number 666 while exploring sites in Egypt and Turkey. He discovers an inscription in southern Egypt at the Philae Temple in Aswan, which reads, "He is many men and no man, towering like the sphinx, dead and alive, but who knows what he thinks? Back from the Styx; 666." Who is this sphinx-like man? Could h...