What books MUST be included?
Classics, i.e., Homer, Plato, etc.
Books covering the horrors of man, hopefully so they are not repeated. Example: books about the Third Reich, the holocaust (man's inhumanity to man).
What books should be explicitly excluded?
Comic books
Historical documents should be included. The Declaration of Independence, but as an American I am proudly biased.
Music, in some format, should be included. It is a universal language that evokes thought and emotion.
Music would be very good, but the pre technological target audience could only get low quality sound. The few high tech high data density archives are much better suited. We will include maps to their locations for when they can read them.
Maybe musical notation and a xylophone and harmonica??