In plain words
Before it there are two words, ‘upa’ and ‘ni’. ‘Upa’ means near, ‘ni’ means with steadfastness. When we join these three, it becomes ‘upaniṣat’. Its meaning is sitting near the knower of the Veda with steadfastness. Sitting, to do what? To listen with a one-pointed mind to all the teachings this knower of the Veda gave, so that they press close to the heart.
Consciousness fills all places
Hearing such sounds, grasping them, coming to know their meaning and holding it within oneself: this they went on expressing with the word ‘eṟuka’. ‘Eṟuka’ means consciousness. This itself they call cētana. Where is this cētana? This cētana fills all places. The worlds, those who live in the worlds and the lords of the worlds, all of them are forms of consciousness! This is a principle joined with the oneness of both the inert and consciousness. This consciousness is present in man in greater measure. More than in other living beings, this consciousness shows itself in man in many ways. Commonly we think that the eyes are what see, the ears what hear, the mouth what speaks. No, no. Consciousness alone gives sight to the eyes, consciousness alone makes the ears hear sound, consciousness alone makes the mouth speak! Consciousness, dwelling within, gives light to the outer senses and makes it manifest. Consciousness alone is present everywhere. But because man turns his sight outward, he cannot recognise this inner consciousness. That is, it stays unmanifest. When we gradually turn the nature of the senses inward, this light, this consciousness, grows abundantly. It is more evident in great souls than in ordinary men. Divinity itself is consciousness. What is the reason such a difference appears? A small example. Here they have put up small bulbs.