But “Y,” which on his hypothesis should be Xerxes, was not quite so easy to explain. He already knew the values of four or five of the seven signs composing group “Y,” and these known values occurred in the order he expected, but the first and third signs in the group remained to be dealt with. Grotefend observed that the first sign was the same as the first sign of the group correctly guessed by Münter to represent “king”: he ascertained that the Greek letter “x” was transliterated in the Zend by “kh,” and rightly inferred that the Greek “x” commencing the proper name Xerxes would be similarly transliterated by “kh” in old Persian, in other words that the first sign in the group should be read “Kh.” The result of Grotefend’s investigations was the discovery of the correct values for eight letters in the Persian cuneiform alphabet, the letter “a” having been already rightly read by Tychsen and Münter. His method of decipherment was proved to be correct by the quadrilingual vase-inscription already alluded to. The first version of this latter inscription is written in Egyptian hieroglyphics and was deciphered by Champollion as the name of Xerxes. The other three versions are written in cuneiform characters, the first of which, the old Persian, gave precisely the same group of signs as that which Grotefend read as Xerxes on the inscription from Persepolis. As Sayce[39] well says, the decipherment of cuneiform and all the far-reaching consequences resultant from it, depended upon a successful guess, but a guess made “in accordance with scientific method,” and it was upon Grotefend’s discovery that all subsequent attempts to decipher cuneiform—Persian, Median, or Assyrian—were based. But unfortunately, though Grotefend had thus given the clue, and scented the track for all future scholars, his own ignorance of eastern languages prevented him from reaping himself the full harvest of his brilliant commencement, and the work so nobly begun was not completed till a later day. The next great step forward was taken by the French scholar Emile Burnouf in 1836; he discovered that one inscription contained a list of the satrapies, and as the names of the satrapies were known from the Greek writers he was able on the partial knowledge of the alphabet already attained, to fit in the names to the cuneiform signs, and as a result he produced an alphabet of thirty letters mostly correct. About the same time Lassen assigned the correct values to almost all the letters in the alphabet, and further demonstrated that the language of the inscriptions was akin to the language of the Zend and also to the Sanskrit, though identical with neither.