This injunction of civilizing import became the starting point of the activity of all of Ezra's successors, of the so-called school of the _Soferim_, the Scribes, those versed in the art of writing. The political calm that prevailed during the two centuries of the Persian supremacy (538-332 B. C. E.), was calculated to an eminent degree to promote spiritual development and the organization of the inner life of the people. During this period, a large part of the writings after the Pentateuch that have been received into the Bible were collected, compiled, and reduced to writing. The immortal thoughts of the Prophets clothed themselves in the visible garb of letters. On parchment rolls and in books they were made accessible to distant ages. The impressive traditions transmitted from earliest times, the chronicles of the past of the people, the Psalms brought forth by the religious enthusiasm of a long series of poets, all were gathered and put into literary shape with the extreme of care. The spiritual treasures of the nation were capitalized, and to this process of capitalization solely and alone generations of men have owed the possibility of resorting to them as a source of faith and knowledge. Without the work of compilation achieved by the _Soferim_, of which the uninstructed are apt to speak slightingly, mankind to-day had no Bible, that central sun in world-literature. These two centuries may fitly be called the school-days of the Jewish nation; the Scribes were the teachers of Jewry. In the way of original work but little was produced. The people fed upon the store of spiritual food, of which sufficient had been laid up for several generations. It was then that the Jews first earned their title to the name, "the People of the Book." They made subservient to themselves the two mightiest instruments of thought, the art of writing and of reading. Their progress was brilliant, and when their schooling had come to an end, and they stepped out into the broader life, they were at once able to apply their knowledge successfully to practical contingencies. They were prepared for all the vicissitudes of life. Their spiritual equipment was complete.