"Any man has had countless myriads of ancestors and among them any number of rich men and beggars, kings and slaves, Greeks and barbarians"—Plato
This is the Favorite Genealogy Quote of Martin E. Hollick. Martin wrote an excellent article about medieval genealogy for Achives.com
http://experts.archives.com/hollick-martin/medieval-genealogy-for-the-medievally-challenged-like-me.html