This study examines the evolution of Christine's thought on true and false opinion. She reflected deeply on the subject of opinion while analyzing, evaluating, challenging, and changing her own and others' opinions in her lifelong quest for certain truth. Parsing opinion in Christine's writings gives us insight into her thought on controversial issues while highlighting opinions that were and, indeed, often still are, subjective and controversial. The first two chapters treat her definition and description of opinion, including her conception of the thinking mind and the arts by which that mind expresses thought; they also follow her changing opinion about the nature and power of fortune in the world she knew.The next three chapters treat three specific changes in her opinions on misogyny, chivalric (or courtly) love, and self-interest and enlightened self-interest in society. The last chapter relates Christine's views on opinion to recent work on subjectivity in medieval writing.