We say that the Upper World is concealed from us. Why is it called "Upper"? We are surrounded by something that is called the Creator. There is nothing else beside Him. We feel the Creator, but who are "we"? His only creation is the will to receive pleasure and fulfillment.
Kabbalah puts it very simply: the Creator created desire. The Creator in Himself is called Atzmuto and is inconceivable. He is inaccessible to any science. The name "Atzmuto" speaks namely of His inscrutability.