Why bother? -- On being a clown: From three to six months -- The birth of laughter: From three to six months -- Joining society: From six to twelve months -- Mastery is not play: From one to two years -- On the importance of only pretending: From two to three years -- The future of make-believe: From three to four years -- Primitive society-order and disorder: From four to five years -- The dream: From five to seven years -- The absurd: From seven to nine years -- Competence with caring: From nine to thirteen years