With Niebuhr's publication the work of decipherment became possible. In 1798, Professor Tychsen, of Rostock, discovered that in the first system an oblique wedge was used to divide the words from one another, and in 1802 the Danish Bishop, Münter, starting from this basis, showed that the language possessed suffixes, pointed out that certain characters denoted vowels, and even divined the word for 'king,' as well as the value of two letters, one of them being a. He also maintained that while the first system of writing was alphabetic, the second was syllabic, and the third ideographic, and that as the inscriptions were found in Persia and on the buildings of the Achaemenian kings, the text which always comes first must represent the language of ancient Persia, which he identified, though erroneously, with Zend.

It is, however, to George Frederick Grotefend, of Hanover, that the discovery of the key which has unlocked the secrets of cuneiform literature is really due. On September 4, 1802, he read before the Royal Society of Göttingen a Memoir, in which he announced his discovery of the names of certain Achaemenian kings in the cuneiform inscriptions, and explained the method by which he had arrived at his results. By a curious coincidence it was at the same meeting of the Society that Heyne described the first efforts that had been made towards deciphering the Egyptian hieroglyphics. Grotefend first showed convincingly that the inscriptions must be read from left to right, a portion of a word which ends a line on the right side in one of the texts beginning the next line on the left side in a duplicate copy of it. He next pointed out that the analogy of the Sassanian inscriptions, which had just been deciphered by de Sacy, indicated that the Persepolitan texts must commence with the names of the kings who had erected the monuments, followed by their titles, and that a comparison of the texts one with another made it pretty evident that such was actually the case. In this way he succeeded in finding (like Münter before him) the word for 'king,' and in addition to this the royal names preceding it. Those on the Persepolitan monuments represented a father and a son, though in certain cases the father added his own father's name, but without the royal titles. Thanks to the classical writers, it was known that the monuments were of Achaemenian origin, and the names of the Achaemenian kings had also been preserved. It only remained to fit them to the characters in the cuneiform texts. Hystaspes, Darius, and Xerxes alone suited, since Cyrus was too short and Artaxerxes too long; moreover, the letters a, r, and sh, in the names of Darius and Xerxes appeared in their right places if these names were adopted. So, too, did a and sh in the name of Hystaspes. Such a coincidence was sufficient to prove that Grotefend was right in his guess that the words in question represented proper names, for guess it was, though founded on strong probability and scientific induction. He had noticed that two of the names (those of Darius and Xerxes) occurred separately on two particular groups of monuments, whereas the word which followed them was always the same. It was natural to conclude that the latter word denoted 'king,' while those which preceded it were proper names.

The alphabet Grotefend had constructed out of the proper names enabled him to read the word for 'king,' and thus to show its near affinity to the corresponding word in Zend. But he was a classical scholar rather than an orientalist, better known by his Latin grammar than by his knowledge of Eastern languages, and consequently as soon as his pioneering work of decipherment was accomplished, he lacked the philological knowledge which would have allowed him to continue it. Moreover, he was hampered by the false theory that the language of the inscriptions was identical with Zend. The next step of importance was taken by Rask in 1826, who discovered the termination of the genitive plural and the true reading of the title 'Achaemenian.' Rask was followed in 1836 by the great Zendic scholar Burnouf at Paris, and by Lassen at Bonn. Burnouf demonstrated that the language of the Achaemenian texts was not Zend, but a sister dialect spoken in western Persia, and his discovery of the names of the satrapies, in one of the inscriptions copied by Niebuhr, enabled him and Lassen simultaneously almost to complete what we may henceforth call the Old Persian alphabet. A few corrections in it were subsequently made by Beer, Jacquet, Holzmann, and Lassen himself.

Meanwhile a young English officer in the East India Company's service, now Sir Henry Rawlinson, had been working in Persia unassisted, and at a distance from libraries, upon the Old Persian texts. He knew that Grotefend had discovered in them the names of the early Achaemenian monarchs, and with this clue he set himself to construct an alphabet and interpret the inscriptions. He soon found means of providing himself with fuller materials for the work of decipherment than those at the disposal of scholars in Europe, by copying the great inscription which Darius had caused to be engraved on the sacred rock of Bagistana or Behistun in commemoration of his accession to the throne of Persia, and re-conquest of the empire of Cyrus. The task of copying the inscription—by far the longest Persian one known—was an arduous one, and not unattended with danger, and it occupied several years. Rawlinson first saw the inscription in 1835; it was not till 1839 that the whole of it was copied. A few years later he revised it again, but his memoir upon it and upon the other Old Persian texts was not ready for publication till 1845. In the following year the text was published by the Royal Asiatic Society, and the translation and commentary followed in 1849. Dr. Hincks, of Dublin, had already (in 1846) given the last touch to the decipherment of the Old Persian alphabet by the discovery that the consonants composing it contained inherent vowels.

As we have seen, Niebuhr had perceived that the Persepolitan inscriptions were in three different systems of writing. But it was only after the decipherment of the Persian texts that it was found that the three systems of writing embodied three separate languages, and belonged to three separate countries. As in modern Turkey a governor has to issue an edict in agglutinative Turkish, Semitic Arabic, and Aryan Persian, so too in ancient Persia a king who wished to be understood by all his subjects had to appeal to them in the Aryan language of Persian itself, in the Semitic language of Babylonia and Assyria, and in the agglutinative language of Susiania or Elam. When the second and third systems of writing came to be read it was discovered that the second contained the script and language of Elam—sometimes, but incorrectly, called Scythian, Medic or Protomedic, sometimes, more properly, Amardian or Neo-Susian—while the third was Babylonian. The three capitals of the empire, Persepolis, Susa and Babylon, were thus each of them represented.

The number of characters used in Amardian, though large, was limited, and accordingly, with the help of the proper names occurring in the Old Persian texts, a syllabary, or list of characters each expressing a syllable, was soon formed and the work of translation commenced. Westergaard, the Dane, who had already travelled in Persia, and there copied the inscription on the tomb of Darius at Naksh-i-Rustem, led the way in 1845. He was followed by Hincks, de Saulcy, and above all Edwin Norris, the learned Secretary of the Royal Asiatic Society, who published in 1853 the Amardian (or as he called it the 'Scythic') version of the Behistun inscription, with an elaborate translation, commentary, and vocabulary. Further progress, in the study of the language was made by Oppert, whose book Le Peuple et la Langue des Mèdes (1879) is a monument of systematic research. Sayce's decipherment of the inscriptions of Mal-Amir, south-east of Susa, in 1884 (in the Proceedings of the Sixth Oriental Congress), showed that we must look to that part of Susiania for the origin of the Amardian syllabary and dialect. The language was, in fact, one of the agglutinative dialects spoken in Elam, the native language of Susa itself being closely related to it. Unfortunately, however, there is no known language with which the dialects of ancient Elam can be compared, and consequently our knowledge of them hardly extends beyond the help afforded by the trilingual Persian texts.

The decipherment of the third system of writing long seemed to baffle the inquirer. The characters were multitudinous, some of them were plainly ideographs, denoting ideas and not letters or syllables, while the same character did not always appear to have the same value. Moreover, the belief that the characters must represent alphabetic letters long stood in the way of the decipherer. Grotefend had already observed that they resembled in form the characters found on some of the antiquities which came from Babylonia, but it was not till after the excavation of Nineveh that any serious effort was made to decipher them. Botta and Layard, at the very outset, pointed out that the script used in Assyria was the same as that of the third Achaemenian system, and thus attracted fresh attention to the latter. Löwenstern was the first to attack the problem in 1845. His first essays, however, were unsuccessful, like those of de Saulcy in 1847, and his second publication (in 1847) did little more than establish the fact that the same name might be written with different signs. In the same year de Longpérier correctly deciphered the words and ideographs denoting 'palace,' 'king,' 'great,' and the like, though without being able to read phonetically any one of them. But in 1848 Botta published the numerous inscriptions he had discovered at Khorsabad, at the same time subjecting them to a careful analysis. He divided them into words, wherever it was possible, noting the variations in writing the same word, and drawing up a list of 642 classified characters. He further proved that the terminations or suffixes of words in the Assyrian texts agreed with those of the third Achaemenian system, an indication that the language was the same as well as the script. Finally he made it clear that the script contained not only phonetic characters, but also ideographs, and he correctly determined many of these ideographs, including that which denotes plurality. All that was now needed was to discover the phonetic equivalents of the characters.

This was done half a year later by de Saulcy, who analyzed the Babylonian transcript of the Achaemenian inscription at Elwend, and gave phonetic values to 120 characters. He was, however, still under the belief that they represented letters instead of syllables, and was consequently obliged to admit the existence of 'homophones.' The fact that they really represented syllables,—ba, bi, be, bu, &c.—was discovered by Dr. Hincks immediately afterwards (1847 and 1850). Hincks also discovered the name of Nebuchadrezzar in the Babylonian inscriptions, and by the further discovery that an inscription brought from Babylon by Sir Robert Ker-Porter, which was written in the complicated characters of early Babylonia, was a duplicate of one in the 'Neo-Babylonian' characters of the Achaemenian era, he made it possible to read the oldest forms of Babylonian script. From this time forward the work of decipherment went on apace. The Semitic character of the Assyro-Babylonian language, which had been guessed at by Löwenstern, was now put beyond question, and the well-known laws of Semitic grammar came to the help of the student in reading the text. In 1851 Rawlinson published the Babylonian text of the Behistun inscription, and in his commentary upon it announced to a wondering and incredulous world the existence in Assyrian of 'polyphones.' If the method of decipherment were right, it was necessary to assume that the same character could have more than one phonetic value. The cause of this extraordinary fact—which, however, is paralleled in Old Egyptian as well as in Japanese—was soon made clear by Oppert, Hincks, and Rawlinson himself. The Assyrian syllabary, which had originally been a collection of pictorial hieroglyphs, was not the invention of the Semitic Babylonians, but of an earlier people who spoke an agglutinative language, and to whom the name of Accadians or Sumerians was given. When the script was adopted by the Semites, the Sumerian words denoting the objects or ideas for which the characters stood became phonetic values; thus du 'to go' and gub 'to stand' became the phonetic values of the character which had originally been a picture of a human leg.

The interpretation of the Assyrian and Babylonian texts now advanced rapidly, in spite of the smallness of the body of students, and the incredulity of Orientalists, especially in Germany. In 1847 Rawlinson was able to give a fairly complete account of the several varieties of cuneiform writing, and in 1850 he published a translation of the long inscription of Shalmaneser II on the Black Obelisk of Nimrûd. The translation is on the whole marvellously correct, and proves conclusively the soundness of the method on which it was based. The proper names, however, were still but imperfectly read, and it was not till Hincks discovered the names of Jehu and Omri in the inscription (in 1851) that the age of it could be fixed. Shortly afterwards Hincks deciphered the names of Hezekiah and Jerusalem in the texts of Sennacherib, as well as the name of Sennacherib himself, and thus showed that Longpérier had been right in his conjecture that the king of the Khorsabad monuments was Sargon. The foundation of Assyrian grammar was next laid by Hincks in 1855 in a series of remarkable articles on the Assyrian verb, to which the progress of discovery has since added little that is important. A complete and systematic grammar itself was first written by Dr. Oppert in 1860, and eight years afterwards M. Ménant analyzed his results and tested their correctness.

The Decipherment tested.—Orientalists, however, still looked askance at the new science which threatened to dwarf the older Semitic learning. The Council of the Royal Asiatic Society, accordingly, determined to subject it to a conclusive test. Copies of the annals of Tiglath-pileser I, which had been found at Kalah Sherghat, were sent to Rawlinson, Hincks, Fox Talbot, and Oppert; they were asked to translate them independently of one another, and send the translations under seal by a given date to the Secretary of the Society. When the translations were opened they were found to be in substantial agreement. This was in 1857, a year which we may therefore regard as closing the first epoch of decipherment.