It is now well-understood that humans are pattern-making and pattern-seeking creatures. This cognitive behavior helps us learn that Chihuauas, Great Danes and Basset Hounds are all dogs, for instance. It helps us with predictions: when the heat and humidity and air pressure build on a summer day we prepare for a thunderstorm. This behavior can also lead us astray, tricking us into seeking significance or meaning in random events, or can give rise to superstitions (such as "bad luck comes in threes.") For good or for ill, we look for patterns.