This large square jade seal is carved with the characters tao te tsan pao meaning "treasure of the library of Taoist classics." The seal appears to have been designed for official use in a library applied to Taoist texts that had been part of a burgeoning canonical literature during Yuan and Ming times. The large size and particular form of this seal relate it to a long line of official seals beginning in the Han dynasty (206 b.c.- a.d. 220). By Sung (960-1279), the large seals were important symbols of official authority and were used to insure the authenticity of important documents, calligraphy, and paintings. The character shan (mountain) on top of the handle equates the seal with the cosmic pillar forming a link between heaven and the text it imprints.