Montesquieu, _Persian Letters_ (1)

In our discussions of Montaigne's Essays, we considered the form and genre of the text (essay) as mirroring the author's project of discovery (self-discovery, discovery of the New World).  Montesequieu adopts the conventions of a different genre -- that of the epistolary novel.  What is the significance of the letter in the Persian Letters?  What does the letter do, communicate, perform, signify (...)?  You might consider the notions of movement, distance, alterity, authorship, spectatorship, contact.