The Brihadaranyaka Upanishad is one of the Principal Upanishads and one of the first Upanishadic scriptures of Hinduism. A key scripture to various schools of Hinduism, the Brihadaranyaka Upanisad is tenth in the Muktikā or "canon of 108 Upanishads".
Brihadaranyaka Upanishad manuscript page (verses 1.3.1 to 1.3.4)
Brihadaranyaka Upanishad literally means the "Upanishad of the great forests".
The Chandogya Upanishad is a Sanskrit text embedded in the Chandogya Brahmana of the Sama Veda of Hinduism. It is one of the oldest Upanishads. It lists as number 9 in the Muktika canon of 108 Upanishads.
The Chandogya Upanishad verses 1.1.1-1.1.9 (Sanskrit, Devanagari script)
The Chandogya Upanishad describes natural phenomena such as a thunderstorm as a form of chant.
Ahimsa - non-violence in action, words and thoughts - is considered the highest ethical value and virtue in Hinduism. The Chandogya Upanishad makes one of the earliest mentions of this ethical code in section 3.17. Above: non-violence sculpture by Carl Fredrik Reutersward.
The Chandogya Upanishad (7th chapter) discusses progressive meditation as a means to Self-knowledge.