Language

And it would seem that human language itself presupposes multiplicity, or at least multiple words.  And by multiple words, I mean words that are different from each other.  You can't form a sentence by stringing together multiple copies of the same word. "Hat hat hat hat hat" is not a sentence.  It would seem that at a minimum we need a noun and a verb, as in "I run."  Maybe not.  Is that a sentence?  Is the command, "Run!" a sentence? Or are we dealing with semantics here?
In any event, I believe we can say that effective language requires multiple words.  And that may be what distinguishes human language from that of animals.  Generally, when I hear one of my pets vocalizing, he or she seems to be stringing together multiple copies of the same word.  When we speak, we string together different words, and when we do so, we do so according to grammatical rules that vary from language to language.  
However, the stringing together of different words appears to be a prerequisite.  Thus, we see the "and" and "or" at work here once again.  The "or" is at work in the differentiation between different words, the fact that they must be different in order to form a sentence.  The "and" is at work in the sense that these words must work together or cooperate in order to form a sentence.
And effective writing requires a high degree of connectivity between different sentences.  Sentences that do not relate to each other are disjointed, and disjointed writing is difficult to absorb.  This cooperation must be at work on a macro level as well.  Paragraphs should be connected by transitions.  If you are writing an essay or a legal brief, you will generally establish a road map exhibiting your plan, your ideas and the connection between them, and you will then seek to expand upon upon them.  A book may have a table of contents, and a preface or introduction telling a reader what to expect.  It will have a high degree of cohesiveness.
Thus, effective expository writing, like everything else, requires a balance between the "and", this cohesiveness and connectivity, and the "or", the use of different words.  If the "and" is overdone, the writing becomes repetitive, and the reader loses patience.
In creative writing or poetry, the writer may test these linguistic boundaries.  A novelist may play with the temporal order we are accustomed to.  He may attempt to surprise the reader with sentences, words or paragraphs that come out of the blue, or a novel and wonderful use of words.
A poet, on the other hand, may not even follow the rules of grammar.  Different lines, stanzas and images may appear disconnected.  It is left to the reader to connect these disparate elements, or just to experience them, and this effort will hopefully prove enriching.
Thus, expository writing requires a greater use of the "and".  Creative writing relies more heavily on the "or" and leaves it to the reader to supply the "and.
Thus, effective expository writing