In a painting, whatever pulls your eye to it first creates the axis. Everything on either side if that axis has some degree of pulling power, and that pull
gives it visual weight. The strength of that pull is determined four things:
(1) Its location between the axis and the sides of the painting,
(2) Its
distance from the bottom of the painting,
(3) The degree of emphasis you put on the image,
(4) the direction and speed of the movement within the image.