As it considers the upanishads as important texts, it raised some questions.
Since both upanishads and vedic texts was written during a very long time span - what makes a text get the status as a vedic or upanishadic?
And next question: is it so that all upanishads are part of vedas? In that case, what makes them separable from other vedic texts?
Age, ancientness. What are considered part of Vedas are: Brahmanas (1), Aranyakas (2) and Upanishads (3). They contain very old material, though it is very difficult to sort out what is new and what is old. Among the Upanishads 13 or so are considered very old and they are most respected. They are known as '
Mukhya Upanishads' (Principle or Main Upanishads). Two of the Upanishads are very short - Mandukya (12 verses) and Ishavasya (18 verses). People kept on writing Upanishads in later times as well, but these don't get the same respect and are mostly associated with sects of Hinduism.
from Wikipedia
Vedas - Wikipedia and other related pages.
Samhita (Vedas proper): Samhita literally means "put together, joined, union", a "collection", and "a methodically, rule-based combination of text or verses". Samhita also refers to the most ancient layer of text in the Vedas, consisting of mantras, hymns, prayers, litanies and benedictions.
- For example, Taittiriya Samhita of YajurVeda was written prior to 2,000 BC.
Parts of Vedic Samhitas which constitute the oldest living part of Hindu tradition:
(1) comment and explain the rituals as well as expound on their meaning and many connected themes.
(2) "wilderness texts" or "forest treaties", were composed by people who meditated in the woods as recluses and are the third part of the Vedas. The texts contain discussions and interpretations of ceremonies, from ritualistic to symbolic meta-ritualistic points of view.
(3) ancient Sanskrit texts that contain some of the central philosophical concepts and ideas of Hinduism. Upanishads are not concerned with rituals, they are concerned with philosophy.
The Sanskrit term Upaniṣad (from upa "by" and ni-ṣad "sit down") translates to "sitting down near", referring to the student sitting down near the teacher while receiving spiritual knowledge.