It's a secret (2)

(Continuation from Sunday)
One of the most common ideas in steganography is to hide the message inside some other writing. The most famous example of this was during the Civil War when a royalist prisoner received an apparently innocuous letter which read the right way (taking the third letter following every punctuation mark) spelled out the whereabouts of a secret passage out of the castle where he was being held allowing him to escape. But such methods were time and labour intensive, and as the need for secret messaging became more and more a commercial matter (firms not wanting their competitors to know what they were up to) something easier and faster was needed, and steganography slowly gave way to cryptography - of which more next time.