What constitutes value in material culture.

1. Historical importance. - basically does the map show something new for the first time in a major way, not just a few corrections.  Seymour Schwartz's book "The Mapping of America" is the bible for serious collectors.  He illustrates most of the most important maps in American History. 2. Aesthetics - Do the design motifs in the cartouche and the rest of the image exceed the norm for the time period when the map was issued.  Is the color great? 3. Condition - is the sheet in the condition that is was when it was first issued, published, and sold.  What has happened to the sheet since then?  The only accretive changes are the oxidation of the iron in the ink - ferrous oxide, the oxidation of the copper in the green - cuprous oxide, the patina of the paper, and the slight unraveling of the cellulose that constitutes paper.  Tears, cut margins, new color, mold stains, foxing, notations greater than 25 years after publication are ALWAYS negatives and detract from the value 4. Rarity - important but exclamations of rarity are generally the refuge of the ignorant or dishonest seller.  Rarity is only truly significant when the first three items on this list are at the highest level.  And lastly but hard to find - Provenance of someone whose actions using this object of material culture changed in a meaningful way the course of history.