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。当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,亚述人在黏土片上刻写书信,然后把信密封在 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. When the other shaves off the slave’s hair, he knows the content of the letter. Before the invention of paper, humans used this peculiar “envelope.” In the 10th century AD, Assyria wrote letters on clay sheets and sealed it up