ABSTRACT
In the modern world a letter is instantly recognizable by its opening formula of address and closing convention, both of which customarily contain polite expressions of friendly greeting. A recent clear-thinking anthologist of Greek and Latin letters has given a bare, rational definition with which it is hard to disagree:
A letter is a written message from one person (or set of people) to another, requiring to be set down in a tangible medium, which itself is to be physically conveyed from sender(s) to recipient(s). Formally it is a piece of writing that is overtly addressed from sender(s) to recipient(s) by the use at the beginning and end of one of a limited set of conventional formulae of salutation (or some allusive variation on them) which specify both parties to the transaction.1
