From
http://shine.yahoo.com/channel/life/the-scoop-on-st-patrick-2465481/:
Patrick's lasting legacyAccording to author Thomas Cahill, Patrick may have been the first person in recorded history to speak out against slavery. In an interview with American Catholic, Cahill remarks: "The papacy did not condemn slavery as immoral until the end of the 19th century, but here is Patrick in the fifth century seeing it for what it is. I think that shows enormous insight and courage and a tremendous 'fellow feeling'—the ability to suffer with other people, and to understand what other people's suffering is like.