On the letter from a friend

What does the letter from a friend do?  First, it arrives.  It arrives with the markings of its travels.  It comes from far away; it is sent, carried, delivered.  Second, it comes from the past.  The letter from a friend is always what was written.  It is memory and not speech.  It is then, and not now.  In demanding my entire gaze, it is immediate, and yet disconnected from the response it requires.  The letter from a friend presupposes its response.  A phone call could be made, an email sent.  But none of these are really appropriate to the gesture of the letter from a friend, which requires another letter from a friend in reply, just as the page on which it is written has two sides, one of which is filled, drawing attention to the opposite, which is blank.