信封溯源寄信用信封,其直接目的是保守秘密。为此,古希腊奴隶主曾剃光奴隶的头发,把“信”写在头皮上,待奴隶头发长长后,再将“信”遣往收件人。对方剃去奴隶的头发,便可知道“信”的内容。在纸发明以前,人类使用的就是这类奇特的“信封”。公元10世纪,亚述人在粘土片上刻写书? Envelopes trace back to credit envelopes, the immediate purpose is to keep the secret. To this end, the ancient Greek slaves had shaved slaves hair, the “letter” written on the scalp until the slave hair length, and then “letter” sent to the recipient. The other shaved off the slave’s hair, you can know the “letter” content. Before the invention of paper, humans used this peculiar “envelope.” Assyria wrote a book on clay in the tenth century AD