Ships? What do you mean, ships?

The story is told of Captain Cook's seventeenth century voyages of exploration to the South Pacific islands. On some he was greeted with spontaneous hospitality, on others with quite natural hostility and on a few with completely blank incredulity. It's easy enough to understand and explain the extremes of human warmth and warrior aggression that his arrival in tall ships, with funny hats and firesticks provoked but it's perhaps more instructive to think for a moment about the blank stares of total incomprehension.

Those Polynesian eyes were not seeing anything at all because there was no response from the brain when it was required to provide a stored reference point. We can't see things at first that are outside our experience. We do however manage to see things that aren't there because want them to be there or because they were there last time we looked. We look with our imagination and in our past.

Derivatives? What do you mean derivatives?