What started Modern Art?

Early Modern art painters like Vincent van Goth, Paul Cezanne, Paul Gauguin, Georges Seurat and Henri De Toulouse Laurence contributed to modern art. I have given a link on modern art in another post on similar topic. The history of modern art can easily be found by Google search.

We mock at modern art that something which cannot be understood by common man.

Modern art is a one which is very simple one to look at but has a concept in it.