In prison he pursued the Vedic studies which had already given him a place in oriental scholarship. His elaborate paper on " The Orion, or Researches into the Antiquity of the Vedas," read at the International Congress of Orientalists, London 1892 (published at Poona, 1893), was followed in 1903 by his " Arctic Home in the Vedas " - expounding a theory of extremely remote Aryan origins which has failed to secure the acceptance of other scholars.
According to Chinese documents they came from the Selenga; but most Orientalists identify them with the Uighurs.
Dupin, and Jean Le Clerc (Clericus), of the orientalists John Lightfoot, John Spencer and Humphrey Prideaux, of John Mill, the collator of New Testament readings, and John Fell, furnished new materials for controversy; and the scope of Spinoza's Tractatus theologico-politicus had naturally been much more fully apprehended than ever his Ethica could be.
Howorth, History of the Mongols (1876-1880); 6th Congress of Orientalists, Leiden, 1883 (Actes, part iv.
Of the Matla`u's-Sa'dain - a choice Persian MS. work of 1495 - introduced to Orientalists in Europe by Hammer, Jahrbucher, Dorn and (notably) Quatremere.