Emperors used seals to proclaim their decrees to their people,
officials used seals to exercise their power,
merchants used seals to demonstrate their credibility ,
landlords used seals to enclose fields,and
the common people used seals to protect their small properties.
Gradually,seals became the personal identity, and even today we are still using seals.
原文：http://www.cnblogs.com/wangshixi12/p/4107876.html