Through the efforts chiefly of Gerhard Tychsen, professor at Rostock, Frederick Muenter, a Danish scholar, and the distinguished Silvestre de Sacy of Paris, the beginnings were made which finally led to the discovery of the key to the mysterious writings, in 1802, by Georg Friedrich Grotefend, a teacher at a public school in Goettingen.

The observation was made previous to the days of Grotefend that the inscriptions at Persepolis invariably showed three styles of writing.

While in all three the characters were composed of wedges, yet the combination of wedges, as well as their shape, differed sufficiently to make it evident, even to the superficial observer, that there was as much difference between them as, say, between the English and the German script.

The conclusion was drawn that the three styles represented three languages, and this conclusion was strikingly confirmed when, upon the arrival of Botta's finds in Europe, it was seen that one of the styles corresponded to the inscriptions found at Khorsabad; and so in all subsequent discoveries in Mesopotamia, this was found to be the case.

One of the languages, therefore, on the monuments of Persepolis was presumably identical with the speech of ancient Mesopotamia.