Lady reason is a virtue developed by Christine, in her book of the City of Ladies. She answers Christine's question on why some men slander women, lady reason tells Christine to "take the spade of her intelligence and dig deep to make a trench all around the city... and reason will help to carry away the hods on earth on (her) shoulders'' in reference to her beliefs. Reason teaches and helps Christine to dispell her own self-consciousness and negative thoughts of past writers.
Lady reason lives to her name concerned with pure reason whose objection to men is that they are mean and that their arguments don't stand up to reasonable questioning.
Lady reason does not only help Christine but other readers. She gives women reason to believe that they are not evil or useless creatures but instead have a significant place in the society