the past is still relevant to the present

There is a Chinese saying that goes "The past can still be used in the present."

My interpretation goes beyond the literal that says traditions should be still practised in modern days. My thoughts are that the powerful at present make use of the dead to keep themselves in power.Whether their bodies are mummified or even their mere picture inspires blind obedience,the dead can be powerful tools to be used by the present to serve their purpose.Can the dead ever rest in peace ? when can they be let go of?
the pharoahs wanted to extend their power from the afterlife,the dead leader is preserved forever,the dead is immortalised or expected to enrich the present?