Then came the philosophers. The work of the Upanishads seems to have ended at that point; the next was taken up by the philosophers. The framework was given them by the Upanishads, and they had to fill in the details. So, many questions would naturally arise. Taking for granted that there is but One Impersonal Principle which is manifesting Itself in all these manifold forms, how is it that the One becomes many? It is another way of putting the same old question which in its crude form comes into the human heart as the inquiry into the cause of evil and so forth. Why does evil exist in the world, and what is its cause? But the same question has now become refined, abstracted. No more is it asked from the platform of the senses why we are unhappy, but from the platform of philosophy. How is it that this One Principle becomes manifold? And the answer, as we have seen, the best answer that India has produced is the theory of Maya which says that It really has not become manifold, that It really has not lost any of Its real nature. Manifoldness is only apparent. Man is only apparently a person, but in reality he is the Impersonal Being. God is a person only apparently, but really He is the Impersonal Being.