Before photography and the toothpaste advertisement were invented, visual portrayal of the human face was mainly presented in a narrow range of expression between solemn and vaguely pleasant. Both sitters and painters must have been agreed upon it. That faint smile on the lips of Leonardo's ''Mona Lisa'' would not be famous had it been more common. And one supposes that most artists would say laughter was impossible to paint.
Two notable exceptions, Frans Hals and Robert Henri, felt that laughter was acceptable as a subject, and was also paintable. An ocean and three centuries separated the Dutch late-Renaissance artist and the American, but the similarities are striking. Both employed a swift, spontaneous brushstroke that tolerated no niggling details of costume or background. The vitality of the model was more important than meticulous technique. Both left many portraits of everyday, anonymous people. Both painted children with a rare appreciation of their joy.
The American, Robert Henri, studied in Philadelphia, which was the art center of the United States in his day. He then spent time in Europe absorbing the art of the masters in the museums. Although one might wonder if his brushstroke would have been quite so bold and his presentation of laughter so irresistibly confident had he not seen examples of Hals's work, Henri consciously chose very American subjects (he pronounced his name in a very Americanized ''hen-ree,'' instead of the original ''on-ree''), and he had his own very definite ideas on the subject of laughter projected with paint on canvas. In his book, ''The Art Spirit,'' he says: ''A laughing head should be organic; that is, all related.... Idea of face all bound together and tight as a clasped hand, idea of pressure. A laughing mouth is stretched, the chin projects, nose and upper lip shortened, the nostrils spread, and eyes squeezed with ends lifted. The spirit of laughter lights up a room. It spreads out over the whole canvas. The body should be laughing as well as the face. The laughter should pass from the beginning of the hair to the ends of it. In the picture of a laughing boy, the laughter should be continued in the hair, carrying out the lines of the features, and a chatter should be in the background. The whole canvas should be like a laughing person coming into a room.''
Did Henri write those lines before painting this endearing portrait or after? As either a description or as a guide, they could not be more apt. Notice the tightness in the modeling of the small face as the little boy's laughter stretches across it. Brushstrokes of flesh-colored paint take the laughter of the face out into and through the sandy hair. His loose, bulky, smocked shirt (c. 1907) ripples with bright white highlights and bluish shadows hinting at a laughing body underneath. Does the dark greenish background chatter? Perhaps it does; it certainly emphasizes the light rosy tones of the face.
Most of Henri's portrait heads have vague, dark backgrounds. When he brought back to New York paintings of the people of the Southwest, he was reproached for not putting in background details. But he was not interested in ''local color,'' sociological analysis of their plight, or sentimental romanticizing; it was his view that an individual's whole life was in his expression, eyes, and movements. This is what he painted.
Although at the height of his career he was considered one of America's top artists, references now emphasize his extraordinary teaching ability. He taught in Philadelphia, Paris, and New York, exhilarating his students with exhortations to express their own individuality and not to conform with current academic modes and techniques.
The quotation above demonstrates his unusual method of teaching art and stimulating his students. There are few directions for combining pigments in ''The Art Spirit'' but a wealth of nuggets about art, humanity, and the appreciation of both. Many of the ranking artists of his day had had him as teacher or mentor.
Although he married twice, there is no record of children. But his love and respect for children is evident in his painting and his writing. He may have been the first to talk about the dignity of a child. ''Feel the dignity of a child. Do not feel superior to him, for you are not,'' is one of many precepts about painting children which reveal ''a high estimate and a great reverence for the child, an unsentimental but a just appreciation of the wonder before him,'' feelings he ascribes to another painter of children, Renoir.
In this small canvas Robert Henri has given us a painting of a small laughing wonder that expresses much about the artist, childhood, and a laughter that could light up a room or a museum gallery.