In this collection of essays, Erickson investigates the ways in which concepts and issues relating to the Church's life have developed in the past and continue to challenge Christians in the present. Some take as their point of departure certain words - canon, priest, heretic - whose meaning and resonance has quietly but significantly shifted over the centuries. Others explore changes in words and images used to express mysteries like forgiveness and reconciliation or to describe the Church's structures for unity and community. Still others examine in historical perspective the issues dividing Christians of East and West; they discuss not only the ways by which the church's unity and continuity have been perceived and expressed over the centuries but also the problems of disunity and discontinuity.