The solution of criminal mysteries constitutes one of the most absorbing, possibly the most intriguing forms of mental activity. It calls for something more than mere cold intelligence and reasoning ability, requiring in addition native perception, intuition, and a natural understanding of human behaviour about under the stress of emotion and passion. Furthermore, some knowledge of pathological or abnormal behaviourism is a requisite.
It would be well for the listener interested in successfully solving these problems to endeavour to think, not as a detective, but as the criminal in the case would think, in order to arrive at a correct solution.