על חיי משה, ספר ב ה׳On the Life of Moses, Book II 5

א׳
1[25] That the sanctity of our legislation has been a source of wonder not only to the Jews but also to all other nations, is clear both from the facts already mentioned and those which I proceed to state. 
ב׳
2[26] In ancient times the laws were written in the Chaldean tongue, and remained in that form for many years, without any change of language, so long as they had not yet revealed their beauty to the rest of mankind. But, in course of time, the daily,
ג׳
3[27] unbroken regularity of practice exercised by those who observed them brought them to the knowledge of others, and their fame began to spread on every side. For things excellent, even if they are beclouded for a short time through envy, shine out again under the benign operation of nature when their time comes. Then it was that some people, thinking it a shame that the laws should be found in one half only of the human race, the barbarians, and denied altogether to the Greeks, took steps to have them translated.
ד׳
4[28] In view of the importance and public utility of the task, it was referred not to private persons or magistrates, who were very numerous, but to kings, and amongst them to the king of highest repute.
ה׳
5[29] Ptolemy, surnamed Philadelphus, was the third in succession to Alexander, the conqueror of Egypt. In all the qualities which make a good ruler, he excelled not only his contemporaries, but all who have arisen in the past; and even till to-day, after so many generations, his praises are sung for the many evidences and monuments of his greatness of mind which he left behind him in different cities and countries, so that, even now, acts of more than ordinary munificence or buildings on a specially great scale are proverbially called Philadelphian after him.
ו׳
6[30] To put it shortly, as the house of the Ptolemies was highly distinguished, compared with other dynasties, so was Philadelphus among the Ptolemies. The creditable achievements of this one man almost outnumbered those of all the others put together, and, as the head takes the highest place in the living body, so he may be said to head the kings.