The Isha Upanishad is one of the shortest Upanishads, embedded as the final chapter (adhyaya) of the Shukla Yajurveda. It is a Mukhya (primary, principal) Upanishad, and is known in two recensions, called Kanva and Madhyandina. It is a key scripture of the Vedanta sub-schools, and an influential Sruti to diverse schools of Hinduism. The name of the text derives from its incipit, "enveloped by the Lord", or "hidden in the Lord (Self)". The text discusses the Atman (Soul, Self) theory of Hinduism, and is referenced by both Dvaita (dualism) and Advaita (non-dualism) sub-schools of Vedanta. The root of the word Ishvara, which means "capable of" and "owner, ruler, chief of", ultimately cognate with English word, own. The word Isha literally means "ruler, master, lord". The term literally means "hidden in, covered with, enveloped by". Isha Upanishad is the only Upanishad that is attached to a Samhita, the most ancient layer of Vedic text known for their mantras and benedictions. The 8th-century Indian scholar Adi Shankara, in his Bhasya (review and commentary) noted that the mantras and hymns of Isha Upanishad are not used in rituals, because their purpose is to enlighten the reader as to "what is the nature of soul (Atman)?"; Enveloped by the Lord must be This All — each thing that moves on earth. With that renounced, enjoy thyself. Covet no wealth of any man. — Isha Upanishad, Hymn 1 The term "This All" is the empirical reality, while the term "renounced" is referring the Indian concept of sannyasa, and "enjoy thyself" is referring to the "blissful delight of Self-realization". The Advaita Vedanta scholar Shankara interprets the above hymn 1 as equating "the Lord" as the "Atman" (Soul, Self). In contrast, Madhvacharya, the Dvaita Vedanta scholar interprets the hymn as equating "the Lord" as Vishnu, or a monotheistic God in a henotheistic sense. Should one wish to live a hundred years on this earth, he should live doing Karma. While thus, as man, you live, there is no way other than this by which Karma will not cling to you. Those who partake the nature of the Asuras, are enveloped in blind darkness, and that is where they reside who ignore their Atman, Self and Soul. For liberation, know your Atman, which is motionless yet faster than mind, it is distant, it is near, it is within all, it is without all this. It is all pervading. And he who beholds all beings in the Self, and the Self in all beings, he never turns away from It. — Isha Upanishad, Hymns 2-6 Uselessness of all rituals, may be necessary to many, nevertheless, to prepare a person for emancipation, to show the path where cravings feel meaningless, and to produce a serene mind that longs for meaning and one that can discern highest knowledge with the necessity of social activity to validate the experiences. The Isha Upanishad suggests that one root of sorrow and suffering is considering one's Self as distinct and conflicted with the Self of others, assuming that the nature of existence is a conflicted duality where one's happiness and suffering is viewed as different from other living being's happiness and suffering. Such sorrow and suffering cannot exist, suggests the Upanishad, if an individual realizes that the Self is in all things, understands the Oneness in all of existence, focuses beyond individual egos and in the pursuit of Universal values, the Self and Real Knowledge. When to a man who understands, the Self has become all things, what sorrow, what trouble can there be, to him who beholds that unity. — Isha Upanishad, Hymn 7 The Isha Upanishad, praises the study of Vidya (Real Knowledge, eternal truths) and Avidya (not Real Knowledge, empirical truths). It asserts that to he who knows both Vidya and Avidya, the Avidya empowers him to overcome death (makes one alive), while Vidya empowers him with immortality. The Real Knowledge delivers one to freedom, liberation from all sorrows and fears, to a blissful state of life. The hymns caution against the pursuit of only manifested cause or only spiritual cause of anything, stating that one sided pursuits lead to darkness. To be enlightened, seek both, suggests the Upanishad. It asserts that he who knows both the real and the perishable, both the manifested not-true cause and the hidden true cause, is the one who is liberated unto immortality. In final hymns, the Upanishad asserts a longing for Knowledge, asserting that it is hidden behind the golden disc of light, but a light one seeks. It reminds one's own mind to remember one's deeds, and accept its consequences. "O Agni (fire) and mind, lead me towards a life of virtues, guide me away from a life of vices", and thus unto the good path and the enjoyment of wealth (of both karma's honey and Self-realization). The final hymns of Isha Upanishad also declare the foundational premise, "I am He", equating one soul's oneness with cosmic soul. I am He, the Purusha within thee (Shiva). — Isha Upanishad, Hymn 16