Final answer:
Purgatory and Mary's sinlessness developed during the late medieval devotional writing period.
Step-by-step explanation:
The concepts of purgatory and Mary's sinlessness developed during the period of Late medieval devotional writing, which took place from the 13th-15th centuries. During this time, there was a shift towards mysticism in devotional writings, and various writers, such as St. Bonaventure and St. Bridget of Sweden, imagined Mary's thoughts as she held her dead son. The growing importance of Mary within Christian practice led to a new focus on charity within the Church.