"Read between the lines"
Posted by Robert Rust on November 23, 2001
I recently wrote a term paper about "steganography", the practice of secretly hiding a message inside another seeminingly innocent message. A prime example of steganography is the use of invisible inks. The most common form of invisible writing from ancient times was the use of invisible inks, which darken when heated. This allowed writing hidden messages "between the lines" of an innocent letter. Common sources for invisible inks were milk, juices and even urine. Perhaps this is where the term "read between the lines" was developed.....justa thought