When the ancient Chinese had secret techniques, didn't they try to keep them in the family, unwilling to reveal them even when offered princely sums?
回顧中國科技史，先人有獨門秘方時，不也是嚴藏密防，「傳子不傳賢」；無人可傳時，寧可付之一炬也不願公諸於世。