No other major Western philosopher so signalizes the turn towards India, combined with a disenchantment with the European-Christian tradition. He proclaimed the concordance of his philosophy with the teachings of Vedanta. His contribution to the propagation and popularization of Indian concepts has been considerable.
(source: India and Europe: An Essay in Understanding - By Wilhelm Halbfass p. 436).
"There is no religion or philosophy so sublime and elevating as Vedanta."
(source: Kumbha Mela - By Jack Hebner and David Osborn p. preface - By Thomas Beaudry).
Schopenhauer became acquainted with the thought of the Upanishads through a Latin translation from Persian by a Frenchman, Anquetil Duperron. His eulogy is well known.
"The Indian air surrounds us, the original thoughts of kindred spirits.....And O! how the mind is here washed clean of all its early ingrafted Jewish superstition! It is the most profitable and most elevating reading which is possible in the world."
(source: Eastern Religions and Western Thought - By Dr. S. Radhakrishnan p 248 and Hinduism Invades America - By Wendell Thomas p. 240 published by The Beacon Press Inc. New York City 1930).
"How entirely does the Oupnekhat (Upanishad) breathe throughout the holy spirit of the Vedas! How is every one, who by a diligent study of its Persian Latin has become familiar with that incomparable book, stirred by that spirit to the very depth of his Soul!
(source: Harvest Fields).
Schopenhauer was in search of a "philosophy which should be at once ethics and metaphysics." India did not disappoint him. He found it in the Upanisadhic "tat twam asi", "that thou art".
"From every sentence (of the Upanishads) deep, original and sublime thoughts arise, and the whole is pervaded by a high and holy and earnest spirit...."In the whole world there is no study so beneficial and so elevating as that of the Upanishads. They are destined sooner or later to become the faith of the people."
Schopenhauer, who was in the habit, before going to bed, of performing his devotions from the pages of the Upanishads, regarded them as:
" It has been the solace of my life -- it will be the solace of my death."
(source: The Discovery of India - By Jawaharlal Nehru Oxford University Press. 1995. pg 92 and The Upanishads Translated for the Modern Reader By Eknath Easwaran Nilgiri Press. 1987 p. 300 and Outlines of Hinduism - By T. M. P. Mahadevan - p.30).
He anticipated later speculations with his claim that Christianity had "Indian blood in its veins" and that the moral teachings of the New Testament had their historical source in Asia beyond Israel: "Christianity taught only what the whole of Asia knew already long before and even better"
(source: Oriental Enlightenment: The encounter between Asian and Western thought - By J. J. Clarke p.68-69).
To Schopenhauer the Upanishads were documents of 'almost superhuman conception,' whose authors could hardly be thought of as 'mere mortals.'
He also remarked: "How every line is of such strong, determined, and consistent meaning! And on every page we encounter deep, original, lofty thoughts, while the whole world is suffused with a high and holy seriousness."
(source: cited in German in Upanishaden: Altindische Weisheit (Upanishads: Ancient Indian Wisdom) - By Alfred Hillebrandt (Dussseldorf-Koln, Germany; Diederichs Verlag, 1964 p. 8).
He spoke of India as the 'fatherland of mankind' which 'gave the original religion of our race,' and he expressed the hope that European peoples, 'who stemmed from Asia,...would re-attain the religion of their home.'
He believed that the Upanishads, together with the philosophies of Plato and Kant, constituted the foundation on which to erect a proper philosophy of representation. It was the Upanishads' analysis of the self which caused Schopenhauer to stamp them as " the product of the highest human wisdom". He dedicated himself to this task, producing his magnum opus, The World as Will and Representation, in 1819. This is what he says in this book:
"We, on the contrary, now send to the Brahmans English clergymen and evangelical linen-weavers, in order out of sympathy to put them right, and to point out to them that they are created out of nothing, and that they ought to be grateful and pleased about it. But it is just the same as if we fired a bullet at a cliff. "In India, our religions will never at any time take root; the ancient wisdom of the human race will not be supplanted by the events in Galilee. On the contrary, Indian wisdom flows back to Europe, and will produce a fundamental change in our knowledge and thought."
(source: The World as Will and Representation - By Arthur Schopenhauer Volume I, & 63 p. 356-357).
Schopenhauer regarded the Hindus as deeper thinkers than Europeans because their interpretation of the world was internal and intuitive, not external and intellectual. For intuition unites everything, the intellect divides everything. The Hindus saw that the "I" is a delusion, that the individual is merely phenomenal, and that the only reality is the Infinite One "That art Thou"
(source: India and World Civilization - By D. P. Singhal Pan Macmillan Limited. 1993. p 254).
Schopenhauer wrote in the preface of his The World as a Will and Representation
"According to me, the influence of Sanskrit literature on our time will not be lesser than what was in the 16th century Greece's influence on Renaissance. One day, India's wisdom will flow again on Europe and will totally transform our knowledge and thought."
Schopenhauer, had extracted from Indian philosophy its contempt for the mere intellect. He admitted extracting his philosophical outlook from the Vedanta and attempting to weld "empirical realism" with transcendental idealism."
"Schopenhauer went on from there to vindicate Indian philosophy's rightful place in the world.." He even went so far as to express pleasure at the continuous failure of West-Christian proselytism in Asia and added: "Our religions will never at any time take root; the ancient wisdom of the human race will not be supplanted by the events in Galilee. On the contrary, Indian wisdom flows back to Europe, and will produce a fundamental change in our knowledge and thought." His anti-Christianism was largely based on a fierce anti-Biblism; .....he attributed systematically to subtle influences originating on the "holy-banks of the Ganga."
(source: The Soul of India - By Amaury de Riencourt p 274-275).
It is well-known that the book 'Oupnekhat' (Upanishad) always lay open on his table and he invariably studied it before retiring to rest. He called the opening up of Sanskrit literature 'the greatest gift of our century', and predicted that the philosophy and knowledge of the Upanishads would becomes the cherished faith of the West.
(source: Western Indologists: A Study in Motives - By P B Dutt http://www.philosophy.ru/
The Upanishads came to Schopenhauer as a new Gnosis or revelation. "That incomparable book," he says, "stirs the spirit of the very depths of the soul."
(source: The Legacy of India - edited By G. T. Garratt p. 32).
Schopenhauer was fond of saying that the first intuition of the work he was to do came to him while reading these texts, of which he was later to say that they had been “his life’s consolation.”
(source: Yoga and the Hindu Tradition - By Jean Varenne p. 186 - 187).