The idea grows and grows, until it attains its climax. In almost all of the Upanishads, we find the climax coming at the last, and that is the dethroning of this God of the universe. The personality of God vanishes, the impersonality comes. God is no more a person, no more a human being, however magnified and exaggerated, who rules this universe, but He has become an embodied principle in every being, immanent in the whole universe. It would be illogical to go from the Personal God to the Impersonal, and at the same time to leave man as a person. So the personal man is broken down, and man as principle is built up. The person is only a phenomenon, the principle is behind it. Thus from both sides, simultaneously, we find the breaking down of personalities and the approach towards principles, the Personal God approaching the Impersonal, the personal man approaching the Impersonal Man. Then come the succeeding stages of the gradual convergence of the two advancing lines of the Impersonal God and the Impersonal Man. And the Upanishads embody the stages through which these two lines at last become one, and the last word of each Upanishad is, "Thou art That". There is but One Eternally Blissful Principle, and that One is manifesting Itself as all this variety.