(9) Relations of contrariety and incongruity • 107 (10) Verbal play and witticism • 111 Co-operation of different laughable features • 114 (11) Manifestations of playfulness in objects • 116 (12) Spectacle of successful combat • 117 CHAPTER V. THEORIES OF THE LUDICROUS. 1. The Theory of Degradation • 119 Aristotle’s theory • 120 Theory of Hobbes • 120 Prof. Bain’s theory • 121 Criticism of theory of degradation • 122 2. Theory of Contrariety or Incongruity • 125 Kant’s theory of nullified expectation • 126 Criticism of Kant’s theory • 126 Function of surprise in effect of the ludicrous • 129 Schopenhauer’s theory of incongruity • 130 Criticism of Schopenhauer’s theory • 132 Different forms of the incongruous • 134 Summary of criticism of theories • 135 Attempts to unify the two principles • 136 The laughable as failure to comply with a social requirement • 139 How primitive laughter comes into effect of the ludicrous • 140 Relation of sudden gladness to release from constraint • 141 Element of contempt in effect of the ludicrous • 142 Laughter and the play-mood • 145 The play-mood in the effects of the ludicrous • 149 Summary of results of inquiry into theories • 153 CHAPTER VI. THE ORIGIN OF LAUGHTER. Problem of the origin of laughter in the race • 155 Supposed rudiments of mirth in animals • 156 The dog’s manifestations of a sense of fun • 159 The mirthful displays of the ape • 162 First appearance of laughter in child: date of the first smile • 164 Date of the first laugh • 166 The laugh as following the smile • 168 Order of the two in the evolution of the race • 170 Conjecture as to genesis of the human smile • 171 How the primitive smile may have grown into the laugh • 173 Problem of the evolution of the laughter of tickling • 176 Effects of tickling in animals • 177 Date of first response to tickling in the child • 177 Tickling as inheritance from remote ancestors • 178 Value of evolutional theories of tickling • 181 How laughter may have come into tickling • 183 CHAPTER VII. DEVELOPMENT OF LAUGHTER DURING THE FIRST THREE YEARS OF LIFE. Problem of the early development of laughter in the individual • 186 Development of smile and laugh as movements • 188 The general process of emotional development • 189 Relation of laughter of joy to that of play • 194 Development of laughter of joy • 195 Emergence of laughter of surprise • 197 First laughter of release from strain • 197 Crude form of laughter of jubilation • 198 Development of laughter as accompaniment of play • 198 Early forms of laughing impishness • 201 First manifestations of rowdyish laughter • 203 Germs of roguish laughter • 205 First crude perceptions of the laughable • 207