This material world is a reflection of the spiritual world. The material world is but a shadow of reality. In the shadow there is no reality or substantiality, but from the shadow we can understand that there are substance and reality. In the desert there is no water, but the mirage suggests that there is such a thing as water. In the material world there is no water, there is no happiness, but the real water of actual happiness is there in the spiritual world.
From Srila Prabhupada’s Introduction to Bhagavad-gita As It Is