Publican in the Bible - a Christian perspective
Jesus was often criticized by the religious leaders of the day for spending time with "unclean" people--publicans (tax collectors) and other people who were considered sinners by society. He responds to that criticism here with the memorable statement that he had come to cure the sick, not to tend to those who were already healthy.
http://biblegateway.com/passage/?search=Matthew%209:11-13&version=KJV