 The traces of classical thought in the encyclopedia, as well as their literary form, equally give an indication that the work was assembled in the course of several decades between the 9th and the first half of the 10th century, and that it may have undergone further elaborations. Such a collective enterprise can be considered as the result of a “stratified” compilation. The supposed reworking of the whole by members of the Brotherhood might also have shifted some Epistles from their original to their present place. Even the headings of the four sections of the encyclopedia are misleading. The way in which the treatises follow one another is often inconsistent. The authors must have planned a special use of the enormous amount of foreign philosophical and scientific knowledge that is explained in the treatises and to develop it in relation to the doctrinal conflicts and political changes that were occurring in their own times. In this sense the presentation of the encyclopedia as a “popular” work (Rudolph, 2004, 39) should be rejected.