What we see is almost always a matter of expectation. No doubt we have evolved to observe the unexpected, to jump to conclusions and then notice departures from those conclusions. How quickly we resolve something to fit what we expect! How outraged we are when what we observe (or are forced to conclude) departs from expectations. It is the well-spring of righteous indignation, a path at the end of which is the au·to–da–fé, heretics burned at the stake, and innumerable lesser acts of violence.

As a little exercise in observing the unexpected - where are the trees in this picture?