William Jones quotes
[T]he mytaphysicks and logick of the Bráhmens, comprised in their six philosophical Sástras... have never yet been accessible to Europeans; and, by the help of the Sanscrit language, we now may read the works of the Saugatas, Bauddhas, A'rhatas, Jainas, and other heterodox philosophers, whence we may gather the metaphysical tenets prevalent in China and Japan, in the eastern peninsula of India, and in many considerable nations of Tartary: there are also some valuable tracts on these branches of science in Persian and Arabick, partly copied from the Greeks, and partly comprising the doctrines of the Súfís which anciently prevailed, and still prevail in great measure over this oriental world, and which the Greeks themselves condescended to borrow from eastern sages.
William Jones
The Sanscrit language, whatever be its antiquity, is of a wonderful structure; more perfect than the Greek, more copious than the Latin, and more exquisitely refined than either, yet bearing to both of them a stronger affinity, both in the roots of verbs and the forms of grammar, than could possibly have been produced by accident; so strong indeed, that no philologer could examine them all three, without believing them to have sprung from some common source, which, perhaps, no longer exists; there is a similar reason, though not quite so forcible, for supposing that both the Gothic and the Celtic, though blended with a very different idiom, had the same origin with the Sanscrit; and the old Persian might be added to the same family.
William Jones