Protagoras
Links
Protagoras
http://www.in2greece.com/english/historymyth/history/ancient/protagoras.htm
Short article summarizing this thinker's thought.
Protagoras
http://www.wikipedia.org/wiki/Protagoras
Brief Wikipedia article on this thinker, noting his relativistic and agnostic teachings.
Protagoras
http://www.iep.utm.edu/p/protagor.htm
Internet Encyclopedia of Philosophy article by Carol Poster. Deals extensively with what we know about the life, doctrines and influence of this Sophist.