Taken as a whole, Atzilut, Beriyah, Yetzirah and Asiyah are one world with three garments. This is because Atzilut itself is not complete except with its garments. However, when we examine these garments individually, each one is called a world in itself. And in truth, each one has a function of its own. Accordingly, when we look at Beriyah, Yetzirah and Asiyah with Atzilut, they can be considered only as the garments of Atzilut. However, when they are considered according to their functions, they are called worlds in themselves.