Monism versus theism The Isha Upanishad is significant for its singular mention of the term "
Isha" in the first hymn, a term it never repeats in other hymns. The concept "Isha" exhibits
monism in one interpretation, or a form of
monotheism in an alternative interpretation, referred to as "Self" or "Deity Lord" respectively. {{Blockquote| 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. Ralph Griffith interprets the word "Isha" contextually, translates it as "the Lord", and clarifies that this "the Lord" means "the Self of All, and thy inmost Self – the only Absolute Reality". 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" (Self). Other interpretations have also been suggested. For example, the more recent scholar
Mahīdhara suggested that hymn 1 may be referring to Buddha, an interpretation that Max Muller stated was inadmissible because of the fundamental difference between Hinduism and Buddhism, with Hinduism relying on the premise "Self, Self exists" and Buddhism relying on the premise "Soul, Self does not exist".
Pursuit of Karma versus pursuit of Self The Isha Upanishad, in hymns 2–6, acknowledges the contrasting tension within Hinduism, between the empirical life of householder and action (
karma) and the spiritual life of renunciation and knowledge (
jnana).
Vidya versus Avidya 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 another 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. 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 12 through 14 of Isha Upanishad, 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 (उभयं सह,
ubhayam saha), 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. {{Blockquote| पुरुषः सोऽहमस्मि I am He, the
Purusha within thee. ==Reception==