Image or Diagram

The Mercator map developed in 1569 was well-suited for seafaring.  A course plotted anywhere on the map matches up with the bearing the ship needs to take in getting from one place to another.  To be truly useful the Mercator map needed to be supplemented by a marine chronometer and a knowledge of the magnetic versus geographical poles, but as a diagram the consequences drawn from its applications were verified and refined by countless navigators.  However, as a result of its success, the Mercator projection of the world came to represent the world for virtually everyone.  The diagram used by sailors became the image in books and classrooms everywhere.

The basis for accepting or rejecting an image is the connection between it and the object it represents.  The map, as an image, should be a precise and accurate representation of that object.  It can be criticized for distorting what it represents, as the Mercator map has been for distorting distances and sizes.  It can be admonished for embellishing or channelling what it represents with subliminal messages regarding other things.  It can be argued that the connection between a map and its object should be more inclusive and exact like a camera or more exclusive and ambiguous like art.  The map as a diagram is also based on an analogy to the object it represents, and that analogy can also be critically assessed; but it, and its analogy, are accepted or rejected on the basis of their functionality.  Diagrams, unlike images, answer to what can be done with them, to how well they work in subsequent applications of it, not to their derivation from, or representation of, the object.