ISHVAR from Sanskrit Isvara (isa = ruler, master, lord+vara= environing, enclosing, i.e. the all-pervasive Lord) is one of the several names used in Indian philosophy for God, the Ultimate Reality, also known as Brahman. There is however a subtle conceptual difference between Isvara and Brahman as interpreted by Sankaracharya, philosopher of Vedanta.
Brahman, he holds, is the Ultimate Reality or Pure Consciousness devoid of all attributes (nirguna) and all categories of the intellect (nirvisesa), while Isvara is the personal aspect of the impersonal Brahman. Isvara is Apara Brahman or Lower Brahman as compared to the Absolute which is called Para Brahma or Higher Brahman. Isvara is the phenomenal aspect of the Transcendent Brahman who is Infinite, beyond the reach of finite thought and who can only be described in negative terms such as ineffable, indescribable, acosmic, timeless, etc. All normal talk about God is therefore about Isvara. Even positive attributes such as transcendent, self-existent, perfect, etc. really refer to "conditioned Isvara" rather than to the "unconditioned Brahman". In brief, Isvara is God as related to the phenomenal reality, the personal aspect of the impersonal Reality. He is the Lord of Maya, the Creator, Sustainer and Destroyer, immanent throughout His creation.
In Sanskrit, isa and isvara are also defined as name of the Hindu gods Shiva, Kubera and one of the Rudras and even as "name of the goddess Durga or any other of the Saktis or female energies of the deities." In Guru Granth Sahib, the Sikh Scripture, Is, Isar or Isuru, Punjabi forms of Sanskrit Isvara, appear sparingly for Shiva as well as for God (GG, 2, 6, 316, 516, 923, 925, 1082); isur once stands for great men is general (GG, 816); and isaru once as name of a person other than Shiva (GG, 952). The composite term paramesar (Sanskrit Paramesvara = parama, supreme, highest + isvara) for God appears more often; once it is spelt even paramesvar (G.G, 299).
Sikhism does recognize the traditional categories of transcendent and immanent as also of nirguna (without attributes) and saguna (with attributes, sarguna in Punjabi), pertaining to God, but not the Sankarite distinction between higher and lower Brahman. The emphasis here is on the unicity of Ultimate Reality, the “1 Onkar”. The term Parbrahma (Sankara’s Para Brahman) appears frequently in the Sikh Scripture but Aparbrahma or Apara Brahman never. For the Sikhs the same Absolute is both nirguna and sarguna (GG, 98, 128, 250, 287, 290, 862). The nirguna Brahman manifests himself as sarguna Brahman, in relation to His attributes.
1. Nirbhai Singh, Philosophy of Sikhism. Delhi, 1990
2. Sher Singh, The Philosophy of Sikhism. Lahore, 1944
3. Ishar Singh, The Philosophy of Guru Nanak. Delhi, 1969
Above adapted from article By Major Gurmukh Singh