The Mapmaker's Blank Square

A cartographer in the late seventeenth century, employed by a modest trading company to produce charts of a region no European had properly surveyed, was famous, among the small guild of his profession, for a peculiar practice. When his information ran out — when he had no reliable data on a stretch of coast, a river's course, the interior of an island — he did not, as most of his colleagues did, fill the space with speculation, ornament, or the classical monsters that decorated the edges of the age's maps. He left the square blank. He wrote across it, in a small hand, the words 'Not known to the maker.'

This drove his employers mad. A blank map, they said, does not sell. A blank map suggests incompetence. A blank map is, from a marketing standpoint, worse than a wrong map, because a wrong map at least looks like a map. Other cartographers of the period fought back by inventing coastlines, populating unknown mountains with fictional rivers, and drawing in, when in doubt, whales.

The cartographer refused. He said, in a letter to his patron that survives, that a map is not a decoration but an instrument, and an instrument that lies in the parts a user does not yet know how to check is worse than useless: it is a betrayal. He would rather be thought lazy than complicit in a captain running his ship onto a coastline the map had invented. He kept the blank squares. He wrote 'Not known to the maker' across each one in his careful hand.

Two hundred years later, when the region was properly surveyed, the coastlines and rivers he had drawn — the ones he had been sure of — proved to be startlingly accurate for their time. The coastlines and rivers his rivals had invented proved, on the same charts, to be nonsense. The trading company that had employed him had long since gone bankrupt in part because it had trusted competitors' fictions over his blanks.

There is a professional and personal version of this problem. In your CV, in your emails, in the small confident sentences you say at dinner about subjects you know only slightly, you are constantly deciding whether to fill in the blank square or to write across it, honestly, 'Not known to the maker.' The temptation to fill it in is enormous, because a blank square looks, in the moment, like incompetence. It is almost always, in the long run, the thing that makes the rest of the map trustworthy.

The people whose judgement you eventually rely on for the important calls in your life will not be the ones with no blank squares on their maps. They will be the ones who label the blank squares clearly. When a captain sets off in a storm, the map with 'Not known to the maker' printed across the coastline is the map that keeps him alive. Draw yours the same way.