1. IshaUpanishad is one of the shortest Upanishads. In just 18 verses it speaks about all that there is to be spoken.
2. On one hand it speaks about the path of renunciation to those who are dispassionate.
3. On other hand, it prescribes path of Karma- a combination of duty & devotion to those having worldly desires.
4. Hence, within its 18 verses it speaks summarizes the entire gamut of Vedas.
5. For God-Realization, one must first overcome the worldly snares like lust, anger etc that stem from desire.
6. Hence, the Vedas prescribe various Karmas & Upasanas that will result in Purification of mind.
7. Due to this,Samhitas & Brahmanas are considered Karma-Khanda.They prescribe path of action to the householders.
8. The Karma-Khanda is considered as Poorva-Bhaga or earlier portion of Vedas.
9. This is because, they instruct students to attain purification of mind without which one cannot understand Vedanta.
10. The Upanishads are termed as Vedanta-the end of Vedas because they teach about the ultimate goal-God Realization.
11. Hence,poorva-bhaga/path of action results in purification & Uttara-Bhaga or path of knowledge results in God-Realization.
12. IshaUpanishad summarizes both the path of action (in conjunction with devotion) & the path of knowledge
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