To the Impressionists, color was not an art property, but a property of light and atmosphere.
Édouard Manet used really very little color, and strong black. He worked with cool and warm [as in classical composition].
Pierre-Auguste Renoir, in his early work, used lots of white, working back in with tints.
Renoir's composition used units of people played against each other.
Whistler and the American Impressionists were subtle, sophisticated, tasteful.
Mary Cassatt's work was light and aesthetic.
Cassatt used different theme colors in different paintings.
Cassatt was a master of both line and paint:
In color, the complement was hidden around in small quantities.
In line, Cassatt contrasted long lines to detail areas.