The freest, purest laughter is that of childhood, which is as spontaneous as the song of birds.  It is impossible that the laughter of older people should retain this sound of perfect music.  Knowledge of life and the world has entered in to mar the natural harmonics of the human voice, which not all the skill and efforts of the vocal culturists can ever again restore.  It is only those who in attaining the years and stature of manhood have retained the nature of the child, its first unconscious truth and simplicity, whose laughter is wholly pleasant to hear.  I recall the laugh of a friend which corresponds to this description, a laugh as pure and melodious, as guiltless of premeditated art or intention, as the notes of the rising lark; yet its owner is a man of wide worldly experience.  It is natural that I, who know my friend so well, should find in this peculiarly happy laugh of his the sign and test of that type of high, sincere manhood which he represents; but it is a dangerous business, this attempting to define the character and disposition of people by the turn of an eyelid, the curve of a lip, or a particular vocal shade and inflection.  Not only has Art learned to imitate Nature very closely, but Nature herself plays many a trick upon our credulity in matters of this kind.  Upon a woman who owns no higher motive than low and selfish cunning she bestows the musical tones of a seraph, as she sheathes the sharp claws of all her feline progeny in cases of softest fur.  Rosamond Vincy is not the only example which might be furnished, either in or out of print, in proof that a low, soft voice, that excellent thing in woman, may have a wrongly persuasive accent, luring to disappointment and death, like the Lorelei’s song, to which the harsh tones of the most strong-minded Xantippe are to be preferred.

Still, it does seem that, however right Shakespeare was when he said a man may smile and smile and be a villain still, no real villain could indulge in hearty, spontaneous laughter.  Much smiling is one of the thin disguises in which a certain kind of knavery seeks to hide itself, but it is easy to conjecture that the low ruffian type of villain, like that seen in Bill Sykes and Jonas Chuzzlewit, neither laughs nor smiles, being as destitute of the courage to listen to the sound of its own voice as of the wit that summons artifice to its aid in protection of its guilty devices.

The ghastly effect of guilt laughing with constrained glee to hide suspicion of itself from the eyes of innocence is vividly portrayed in Irving’s performance of “The Bells,” in the scene where Mathias, by a supreme effort of will, joins in Christian’s laugh over the supposition that it might have been his, the respected burgomaster’s, limekiln in which the body of the Polish Jew was burned.  Genuine laughter must spring from a pure and undefiled source.  It may not always be of tuneful quality, but it must at least contain the note of sincerity.  I have