Gestalt psychologists mostly designed experiments and developed theories to account for perception, and then applied some of their insights to problem-solving. In general, they were strong at identifying interesting and sometimes counter-intuitive phenomena, but were less successful when it came to producing convincing theoretical explanations, which often were just re-descriptions of the data with some fancy (German) labels. Creativity can be seen as a form of problem-solving, except that the problems to be solved (such as discovering a new law in psychology) are more complex than solving puzzles such as the Tower of Hanoi or Maier’s two-string problem. A popular way of characterising thinking is to propose that the cognitive system consists of two kinds of cognition. The first evolved early and is thus shared by many animals. The second kind of cognition is newer evolutionarily, uniquely human, and is characterised by analytical and rule-based thinking that requires attention and effort.