IX[9arg] Of the cypher letters which are found in the epistles of Gains Caesar, and of other secret forms of writing taken from ancient history; and what the Laconian σκυτάλη is.
THERE are volumes of letters of Gaius Caesar addressed to Gaius Oppius and Cornelius Balbus, [p. 235] who had charge of his affairs in his absence. In certain parts of these letters 1 there are found individual characters which are not connected to form syllables, but apparently are written at random; for no word can be formed from those letters. But a secret agreement had been made between the correspondents about a change in the position of the letters, so that, in writing, one name and position was given to one letter and another to another, but in reading its own place and force was restored to each of them. 2 But which letter was written for which was, as I have already said, agreed upon by those who devised this secret code. There is in fact a commentary of the grammarian Probus, On the Secret meaning of the Letters appearing in the Epistles of Gains Caesar, which is a very careful piece of work. But the ancient Lacedaemonians, when they wanted to conceal and disguise the public dispatches sent to their generals, in order that, in case they were intercepted by the enemy, their plans might not be known, used to send letters written in the following manner. There were two thin, cylindrical wands of the same thickness and length, smoothed and prepared so as to be exactly alike. One of these was given to the general when he went to war, the other the magistrates kept at home under their control and seal. When the need of more secret communication arose, they bound about the staff a thong of moderate thickness, but long enough for the purpose, in a simple spiral, in such a way that the edges of the thong which was twined around the stick met and were joined throughout. Then they wrote the dispatch on that thong across [p. 237] the connected edges of the joints, with the lines running from the top to the bottom. When the letter had been written in this way, the thong was unrolled from the wand and sent to the general, who was familiar with the device. But the unrolling of the thong made the letters imperfect and broken, and their parts and strokes 3 were divided and separated. Therefore, if the thong fell into the hands of the enemy, nothing at all could be made out from the writing; but when the one to whom the letter was sent had received it, he wound it around the corresponding staff, which he had, from the top to the bottom, just as he knew that it ought to be done, and thus the letters, united by encircling a similar staff, came together again, rendering the dispatch entire and undamaged, and easy to read. This kind of letter the Lacedaemonians called σκυτάλη. I also read this in an ancient history of Carthage, that a certain famous man of that country —whether it was Hasdrubal or another I do not recall—disguised a letter written about secret matters in the following way: he took new tablets, not yet provided with wax, and cut the letters into the wood. Afterwards he covered the tablet with wax in the usual way and sent it, apparently without writing, to one to whom he had previously told his plan. The recipient then scraped off the wax, found the letters safe and sound inscribed upon the wood, and read them. There is also in the records of Grecian history another profound and difficult method of concealment, devised by a barbarian's cunning. He was called Histiaeus and was born in the land of Asia in no mean station. At that time king Darius held [p. 239] sway in Asia. This Histiaeus, being in Persia with Darius, wished to send a confidential message to a certain Aristagoras in a secret manner. He devised this remarkable method of concealing a letter. He shaved all the hair from the head of a slave of his who had long suffered from weak eyes, as if for the purpose of treatment. Then he tattooed the forms of the letters on his smooth head. When in this way he had written what he wished, he kept the man at home for a time, until his hair grew out. When this happened, he ordered him to go to Aristagoras, adding: “When you come to him, say that I told him to shave your head, as I did a little while ago.” The slave, as he was bidden, came to Aristagoras and delivered his master's order. Aristagoras, thinking that the command must have some reason, did as he was directed. And thus the letter reached its destination.