Criss-Cross Letters

If you received a letter that looked like this, would you expect 1) it was written by a person with psychiatric problems, 2) it was written by a penny-pincher who was trying to save paper, or 3) it was sent to you in order to cause grave emotional trauma? All of these are possible, but there is one correct answer — and many letters like this were written and painstakingly deciphered. More inside.