Richard Woodward writes a great appreciation of Photographer Helen Levitt in the Wall Street Journal:

Like the 20th-century photographers she most admired — Henri Cartier-Bresson, Walker Evans, Manuel Alvarez Bravo — she was drawn to the fraying edges of society. Her identification with people marginalized by income or race was philosophical as well as practical.

The poor are commonly not only metaphoric but literal outsiders, treating the street or public square as the stage where many rituals of daily life are performed. A photographer alert to this vocabulary of poses can capture meanings observable only afterward in the art of a well-resolved image. Levitt had the discerning eye of a choreographer — she had trained in ballet and modern dance — and could spot at a glance the telling gesture: how a 4-year-old’s bent leg and curved arm framed in a doorway lends her body a theatricality the child was only vaguely aware of. [ . . . ] She negotiated these rough streets without fear. (Not so Walker Evans, who balked at going too far uptown with her.) Her true purpose was often masked by the use of a right-angle viewfinder so her subjects would be unaware of being photographed.  [ . . . ] Helen Levitt belongs in that elite group of photographers, along with Brassaï, Robert Capa, André Kertesz, Weegee, and Garry Winogrand, whose pictures still vibrate with the pulse of life captured. As long as people want to look at pictures, hers will continue to astound.

Helen Levitt, Non-Nonsense New Yorker (Wall Street Journal)