The Upanishad, a part of the Vedas, are ancient Sanskrit texts that contain some of the central philosophical concepts and ideas of Hinduism. The Upanishads played an important role in the development of spiritual ideas in ancient India, marking a transition from Vedic ritualism to new ideas and institutions.

The main concept of Hinduism is that of a god-man (or god-adev), who is the creator and ruler of a universe that is inhabited by living creatures. The god-man has a human form and a divine soul.

In Hinduism, the universe is divided into many different worlds, or planes, and we exist in a particular world, which is called our universe. Each world has its own characteristics and is governed by its own laws. Our job is to understand and learn about the world in which we live.