In plain words
The “Brāhmaṇa” portion sets out the use, the purpose and the procedure of these mantras. Though the word ‘Brahma’ has many meanings, here it means mantra. Most of this portion belongs to the path of action in the world. The principles of Vairāgya and the secrets of the Veda are in the ‘Āraṇyaka’. The harmony of these two is in the last portion, the ‘Upaniṣads’. Because this is the final division of the Vedic literature, it came to be called ‘Vedānta’, the end of the Veda. In a way it can be called the essence of the Veda. It is like the butter of the whole Vedic literature. That is, this literature is like the butter that rises to the top when milk is churned. The word Upaniṣad comes from the root ‘sad’. Two prefixes, “upa” and “ni”, are joined to this root. The root ‘sad’ means ‘to sit’, and it has another meaning too, ‘to destroy’. “Ni” conveys steadfastness, niṣṭhā. “Upa” means near. That is, when one learns sitting with steadfastness near the ācārya (near the guru), discernment and wisdom take root. The Bhagavad Gītā, the Upaniṣads and the Brahma Sūtras are the root of Indian philosophy. These are called the ‘Prasthānatraya’, the three foundations. What our eyes see, what makes us forget our body, what delights the Manas, what makes our life shine: that is this physical world. In this earthly world itself is the supreme reality that is not earthly. These two are unbroken parts of one undivided Consciousness. Each is full in itself. Each completes the other. From the full principle of Parabrahman the full principle of the jīva arose. When the body has separated from the jīva, the eternal Consciousness that remains is also the full principle of Parabrahman.