Kazimir Malevich originated the  suprematism art movement, which focused on basic shapes painted in basic colors to show pure art that doesn't try to replicate objects. By creating works that were not influenced by the outside world, he felt he was creating true art. Overall, I feel like the similarity in the two whites is so much that it is hard to see the square as separate from the canvas.  The shades are only distinguishable enough that you can tell there is a white square on a white background., which I think makes it seem less like a square on a canvas, and more like they are connected.  Compositionally, the square seems like it is floating towards the top of the canvas, and creates a sense of freedom.  I think because the square and the canvas are so similar in terms of color, the viewer focuses on the differences between the two, which boils down to size and placement. The smaller square seems to be a part of a separate world, since unlike the  canvas, it is not aligned perfectly with the vertical and horizontal constraints we place on our environment. This small distinction makes the viewer see it as something different and possible foreign.  But fundamentally, the viewer doesn't have to 'see' something such as an object in the piece, but instead focus on obtaining the pure feeling that only pure art can give you.