*   “A mechanical puzzle is a self-contained object, composed of one or more parts, which involves a problem for one person to solve by manipulation using logic, reasoning, insight, luck, and/or dexterity.”
       (Jerry Slocum)
*   "The most beautiful thing we can experience is the mysterious.   It is the source of all true art and science."
       (Albert Einstein, What I Believe (1930))
*   “It is one of man’s curious idiosyncracies to create difficulties for the pleasure of resolving them.”
       (Joseph de Maistre)
*   “A puzzle is a problem or enigma that challenges ingenuity.”
       (Wikipedia)