THE ancient Vedic literature, the foundation of the whole literature of India, which has been handed down in that country in an unbroken succession from the earliest times within the recollection of man to the present day, became known for the first time beyond the frontiers of India through the Upanishads. The Upanishads were translated from Sanskrit into Persian by, or, it may be, for Dârâ Shukoh, the eldest son of Shâh Jehân, an enlightened prince, who openly professed the liberal religious tenets of the great Emperor Akbar, and even wrote a book intended to reconcile the religious doctrines of Hindus and Mohammedans. He seems first to have heard of the Upanishads during his stay in Kashmir in 1640. He afterwards invited several Pandits from Benares to Delhi, who were to assist him in the work of translation. The translation was finished in 1657. Three years after the accomplishment of this work, in 1659, the prince was put to death by his brother Aurangzib, in reality, no doubt, because he was the eldest son and legitimate successor of Shâh Jehân, but under the pretext that he was an infidel, and dangerous to the established religion of the empire.
When the Upanishads had once been translated from Sanskrit into Persian, at that time the most widely read language of the East and understood likewise by many European scholars, they became generally accessible to all who took an interest in the religious literature of India. It is true that under Akbar's reign (1556-1586) similar translations had been prepared, but neither those nor the translations of Dârâ Shukoh attracted the attention of European scholars till the year 1775. In that year Anquetil Duperron, the famous traveller and discoverer of the Zend-avesta, received one MS. of the Persian translation of the Upanishads, sent to him by M. Gentil, the French resident at the court of Shuja ud daula, and brought to France by M. Bernier. After receiving another MS., Anquetil Duperron collated the two, and translated the Persian translation into French (not published), and into Latin. That Latin translation was published in 1801 and 1802, under the title of Oupnek'hat, id est, Secreturn tegendum: opus ipsa in India rarissimum, continens antiquam et arcanam, seu theologicam et philosophicam doctrinam, e quatuor sacris Indorum libris Rak baid, Djedjer baid, Sam baid, Athrban baid excerptam; ad verbum, e Persico idiomate, Samkreticis vocabulis intermixto, in Latinum conversum: Dissertationibus et Annotationibus difficiliora explanantibus, illustratum: studio et opera Anquetil Duperron, Indicopleustæ. Argentorati, typis et impensis fratrum Levrault, (vol. i, 1801; vol. ii, 1802).
This translation, though it attracted considerable interest among scholars, was written in so utterly unintelligible a style, that it required the lynxlike perspicacity of an intrepid philosopher, such as Schopenhauer, to discover a thread through such a labyrinth. Schopenhauer, however, not only found and followed such a thread, but he had the courage to proclaim to an incredulous age the vast treasures of thought which were lying buried beneath that fearful jargon.
As Anquetil Duperron's volumes have become scarce, I shall here give a short specimen of his translation, which corresponds to the first sentences of my translation of the Khândogya-upanishad (p. 1):—
Oum hoc verbum (esse) adkit ut sciveris, sic [tò] maschghouli fac (de co meditare), quod ipsurn hoc verbum aodkit est; propter illud quod hoc (verbum) oum, in Sam Beid, cum voce altâ, cum harmoniâ pronunciaturn fiat.
Adkiteh porro cremor (optimum, selectissimum) est: quemadmodum ex (præ) omni quieto (non moto), et moto, pulvis (terra) cremor (optimum) est; et e (præ) terra aqua cremor est; et ex aqua, comedendum (victus) cremor est; (et) e comedendo, comedens cremor est; et e comedente, loquela (id quod dicitur) cremor est; et e loquela, aïet [toû] Beid, et ex aïet, [tò] siam, id est, cum harmonia (pronunciatum); et e Sam, [tò] adkit, cremor est; id est, oum, voce alta, cum harmonia pronunciare, aokit, cremor cremorum (optimum optimorum) est. Major, ex (præ) adkit, cremor alter non est.
Schopenhauer not only read this translation carefully, but he makes no secret of it, that his own philosophy is powerfully impregnated by the fundamental doctrines of the Upanishads. He dwells on it again and again, and it seems both fair to Schopenhauer's memory and highly important for a true appreciation of the philosophical value of the Upanishads, to put together what that vigorous thinker has written on those ancient rhapsodies of truth.
In his Welt als Wille und Vorstellung, he writes, in the preface to the first edition, p. xiii:
If the reader has also received the benefit of the Vedas, the access to which by means of the Upanishads is in my eyes the greatest privilege which this still young century (1818) may claim before all previous centuries, (for I anticipate that the influence of Sanskrit literature will not be less profound than the revival of Greek in the fourteenth century,)—if then the reader, I say, has received his initiation in primeval Indian wisdom, and received it with an open heart, he will be prepared in the very best way for hearing what I have to tell him. It will not sound to him strange, as to many others, much less disagreeable; for I might, if it did not sound conceited, contend that every one of the detached statements which constitute the Upanishads, may be deduced as a necessary result from the fundamental thoughts which I have to enunciate, though those deductions themselves are by no means to be found there.
If I consider how difficult it is, even with the assistance of the best and carefully educated teachers, and with all the excellent philological appliances collected in the course of this century, to arrive at a really correct, accurate, and living understanding of Greek and Roman authors, whose language was after all the language of our own predecessors in Europe, and the mother of our own, while Sanskrit, on the contrary, was spoken thousands of years ago in distant India, and can be learnt only with appliances which are as yet very imperfect;—if I add to this the impression which the translations of Sanskrit works by European scholars, with very few exceptions, produce on my mind, I cannot resist a certain suspicion that our Sanskrit scholars do not understand their texts much better than the higher class of schoolboys their Greek. Of course, as they are not boys, but men of knowledge and understanding, they put together, out of what they do understand, something like what the general meaning may have been, but much probably creeps in ex ingenio. It is still worse with the Chinese of our European Sinologues.
If then I consider, on the other hand, that Sultan Mohammed Dârâ Shukoh, the brother of Aurangzib, was born and bred in India, was a learned, thoughtful, and enquiring man, and therefore probably understood his Sanskrit about as well as we our Latin, that moreover he was assisted by a number of the most learned Pandits, all this together gives me at once a very high opinion of his translation of the Vedic Upanishads into Persian. If, besides this, I see with what profound and quite appropriate reverence Anquetil Duperron has treated that Persian translation, rendering it in Latin word by word, retaining, in spite of Latin grammar, the Persian syntax, and all the Sanskrit words which the Sultan himself had left untranslated, though explaining them in a glossary, I feel the most perfect confidence in reading that translation, and that confidence soon receives its most perfect justification. For how entirely does the Oupnekhat 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! How does every line display its firm, definite, and throughout harmonious meaning! From every sentence deep, original, and sublime thoughts arise, and the whole is pervaded by a high and holy and earnest spirit. Indian air surrounds us, and original thoughts of kindred spirits. And oh, how thoroughly is the mind here washed clean of all early engrafted Jewish superstitions, and of all philosophy that cringes before those superstitions! In the whole world there is no study, except that of the originals, so beneficial and so elevating as that of the Oupnekhat. It has been the solace of my life, it will be the solace of my death!
Though  I feel the highest regard for the religious and philosophical works of Sanskrit literature, I have not been able to derive much pleasure from their poetical compositions. Nay, they seem to me sometimes as tasteless and monstrous as the sculpture of India.
In  most of the pagan philosophical writers of the first Christian centuries we see the Jewish theism, which, as Christianity, was soon to become the faith of the people, shining through, much as at present we may perceive shining through in the writings of the learned, the native pantheism of India, which is destined sooner or later to become the faith of the people. Ex oriente lux.
This may seem strong language, and, in some respects, too strong. But I thought it right to quote it here, because, whatever may be urged against Schopenhauer, he was a thoroughly honest thinker and honest speaker, and no one would suspect him of any predilection for what has been so readily called Indian mysticism. That Schelling and his school should use rapturous language about the Upanishads, might carry little weight with that large class of philosophers by whom everything beyond the clouds of their own horizon is labelled mysticism. But that Schopenhauer should have spoken of the Upanishads as “products of the highest wisdom” “(Ausgeburt der höchsten Weisheit)”, that he should have placed the pantheism there taught high above the pantheism of Bruno, Malebranche, Spinoza, and Scotus Erigena, as brought to light again at Oxford in 1681, may perhaps secure a more considerate reception for these relics of ancient wisdom than anything that I could say in their favour.
 Elphinstone, History of India, ed. Cowell, p. 610.
 M. M., Introduction to the Science of Religion, p. 79.
 Several other MSS. of this translation have since come to Iight; one at Oxford, Codices Wilsoniani, 399 and 400. Anquetil Duperron gives the following title of the Persian translation: “Hanc interpretationem [tôn] Oupnekhathai quorumvis quatuor librorum Beid, quod, designatum cum secreto magno (per secretum magnum) est, et integram cognitionem luminis luminum, hic Fakir sine tristitia (Sultan) Mohammed Dara Schakoh ipse, cum significatione recta, cum sinceritate, in tempore sex mensium (postremo die, secundo [toû] Schonbeh, vigesimo) sexto mensis [toû] Ramazzan, anno 1067 [toû] Hedjri (Christi, 1657) in urbe Delhi, in mansione nakhe noudeh, cum absolutione ad finem fecit pervenire.” The MS. was copied by Âtma Ram in the year 1767 A.D. Anquetil Duperron adds: “Absolutum est hoc Apographum versionis Latinæ [tôn] quinquaginta Oupnekhatha, ad verbum, e Persico idiomate, Samskreticis vocabulis intermixto, factæ, die 9 Octobris, 1796, 18 Brumaire, anni 4, Reipublic. Gall. Parisiis.”
 M. M., History of Ancient Sanskrit Literature, second edition, p.325.
 Schopenhauer, Parerga, third edition, II, p.426.
 Loc. cit. II, pp. 425.
 Loc. cit. I, p. 59.]
 Loc. cit. 11, p.428.
 Loc. cit. I, p. 6. These passages were pointed out to me by Professor Noiré.