Heres a beautiful painting of the virgin Mary and her bubba, if you look beyond the subject you can see that the reason it is good looking is the relationship of the triangle and the rectangle of the composition.
Similarly Malevich creates beauty by stripping away the content and presenting the triangle and rectangle as they are.
He came up with a style called Suprematism which is about all about shapes, in the same way that a lot of renaissance paintings rely on simply geometric patterns for their compositions.
