Which calligrapher was kept in the cave?

Not locked up. Xizhi Cave is located in Guizong Scenic Area, Wenquan Town, Xing Zi County, Jiujiang City, Jiangxi Province. When Wang Xizhi, a great calligrapher in the Eastern Jin Dynasty, lived in seclusion in Lushan Mountain, he often buried himself in a stone house called Xishi Cave, and raised a group of lovely white geese in the mountain stream outside the cave, but they were not kept in the cave. Wang Xizhi, a native of Linyi (now Linyi, Shandong Province), moved to Yin Shan (now Shaoxing, Zhejiang Province) and lived in seclusion in Jinting County in his later years. Calligraphers in the Eastern Jin Dynasty are known as "book saints".