After sometime, whenhe was walking across the street, he saw an image of Mona Lisa pasted on a window. At once, he knew that was what he needed, something that could make a greater contrast to the keys. He went ahead and painted an image of Mona Lisa behind the keys. Later on, he added a can of Sardines to create some contrast in the image. Apart from the image of Mona Lisa, sardines and keys, he created some abstract images in hues of blue, black, royal yellow, reds and greys. There are also other geometrical angles, shapes and lines cutting across the image.

Fernand Leger followed the Purism style of art. This form of art created relationships between geometric angles and other shapes in the painting. Artists then used colour to enhance a visual effect towards a given point. Colour was also used to create a unified effect on the image. The pure forms in the image created qualities that have no representational meaning.

Purism was built upon cubism, a style of art, which involved the deconstruction of a subject into simple geometrical shapes and a number of interlocking planes. Purists infused industrial and mechanical matter into timeless quality. In the case of Mona Lisa and Keys, keys provided the mechanical aspect of the paint while a mix of colours and shape provided the timeless beauty. In addition, purists rejected the over-embellishing of art pieces that were not in line with real-world, as it was the norm in paintings at the time.

The genre of Mona Lisa with the Keys painting is figurative art. This genre of art has strong references to the real-world items, especially the human figure. In the case of this painting, Mona Lisa is the figure that gives the image its figurative punch. This type of art differs from the popular modern realism in that it uses modern idioms as opposed to post-impressionism type of art. In creating this type of art, Leger Inspired the likes of Picasso and Alberto Giacometti, who created paintings in the 1920s and 1940s. The images were the Weeping Woman of 1937 and the standing Woman Circa in 1964.