Because she painted an ordinary daily moment, contrary to the traditional religious themes or grandiose representations of the Renaissance period. Beyond this fact, there also technical conditions that classify this art as Mannerist, such as the uncared about the sense of beauty, the use of several perspectives points (different from the Renassaince art which uses only one), and the unconcern to proportions depicting tall, long and strange figures.
Explanation:
The better word to describe Mannerism is break up because it was a moment when artists attempt to be contrary to the traditional values incorporated by the Renaissance. Even using some of the features of Renaissance art, Mannerism creates a different art style with the use of colors that do not faithfully represent nature. The colors used in much of the mannerist works are cold, strange and artificial.
Poussin was fascinated by ancient Rome and Italian Renaissance cultures. In his Et in Arcadia Ego that fascination has been translated into a visual text illustrating rational order and classicism. It is reminiscent of which of Raphael.
This painting is by Mary Cassat. She chose to use oil paints. When Cassat chose to use oil paints, she most likely considered that oil paints are slow drying which can make them difficult to work with, but also allow mixing and blending of colors to create various affects. She would have also considered that oil paints are long-lasting and retain their vibrancy over time.
I pretty sure that this is called a Fuge (Lol I didn't spell that right.) As in a Fuge, Its enters at multiple times but still has the same melody throughout.