 The anonymous author of The Book of First and Second Causes (Liber de causis primis et secundis), which dates from the turn of the thirteenth century, does not adopt the distinction between necessary and possible beings, but describes the process of emanation in strongly Avicennian terms: From the first cause issues a first created being, an intellect. From this intellect, in turn, emanates a series of intelligences, the lowest of which is the active intellect. Emanation happens in triads: From an intelligence emanates, in virtue of its intellectual activity, the form of a celestial sphere, the body of a sphere, and another intelligence (ch. 4). The anonymous author also draws on the Book of Causes (see the beginning of section 6 above), for instance when describing the hierarchy of intelligences as a decrease in power and unity (ch. 6).