my favorite description of a spellbook

O ay, it is but twenty pages long,
  But every page having an ample marge,
  And every marge enclosing in the midst
  A square of text that looks a little blot,
  The text no larger than the limbs of fleas;
  And every square of text an awful charm,
  Writ in a language that has long gone by.
  So long, that mountains have arisen since
  With cities on their flanks—thou read the book!
  And ever margin scribbled, crost, and crammed
  With comment, densest condensation, hard
  To mind and eye; but the long sleepless nights
  Of my long life have made it easy to me.
  And none can read the text, not even I;
  And none can read the comment but myself;
  And in the comment did I find the charm.
  O, the results are simple; a mere child
  Might use it to the harm of anyone,
  And never could undo it

--from Lord Tennyson's Idylls of the King, Book V: Merlin and Vivien