It is really enlightening to listen to the Upanishads. I would like to share some of the beautiful ideas from the Chāndogya Upaniṣad commented upon by Shankaracharya.
The world around you is a combination of five great elements. These five come from ‘Sat’ (Pure existence). That is and that alone is the substratum of all the microcosm and macrocosm – “Jagatomoolam”. The five elements are called as Pancha Bhootas. They are the Sky, Air, Fire, Water and Earth.
Our body can’t be separated from Sat. The world is a manifestation of pure existence. The true nature of a substance can’t be separated from object just like the heat or light can’t be separated from fire. True nature remains inseparable. Similarly, you can’t separate Sat from the world around you. From that level of discussion, everything is true. Everything in the world is real if you can see the pure existence in everything. This world is a substratum of divisions.
There are five senses residing in you. Shabda, roopa, gandha, rasa and sparsha. But there is an undivided knowledge inside you. Knowing this and to be in unbroken peace is real meditation.
In waking state, it is impossible to separate the pure existence and the knowledge of the pure existence. To understand it better, consider this statement. “what ever is indicated by the term “This” keeps changing but the term “this” remains unchanged. One can get the correct point if he tries to contemplate on this.
The Upanishads says, though you have strong notions of divisions, it is nothing but pure existence (Sat). World and the objects are dependent on Sat but don’t think that you are enslaved by the world around and the objects around you. Nothing can ever enslave you. Realize it!