 Though the Ikhwân never mention Plotinus explicitly, the third section opens with two treatises that deal with rational beings as understood by the Pythagoreans (Epistle 32) and the Ikhwân al-Safâ’ (Epistle 33). These treatises demonstrate beyond doubt that these authors considered themselves true Muslim Pythagoreans. Pythagoras is said to be “a monotheist from Harrân.” The Pythagorean idea of the one as the principle of numbers, and not as a number itself explains that God is the origin of beings, and not a being like others. If God is like the one, the Active Intellect is compared to number 2, the Universal Soul to number 3 and Nature (or Matter) to number 4 (cf. e.g. Epistle 40, III, 347, 5). The encyclopedia resumes Pythagorean mathematical and musical theories and adopts a numerological approach on the basis of the Pythagorean tenet that “existing beings correspond to the nature of number.” The whole reality is considered under a numerological perspective. Every aspect of nature – and even of religion – follows a numeric pattern. This should demonstrate that the cosmos – also introduced as a “macranthropos” (man as the pattern of the external world as a whole) in Epistle 34 – is organized according to recurrent and well-determined quantitative models, being at the same time completely dependent on God, the principle of everything just as one is the root of each number. According to de Callataÿ, Aristotelian themes are “reshaped”, for didactic purposes, in a Neoplatonic frame (El-Bizri; de Callataÿ 2017, 88), so that those who organized the corpus in its final version “are definitely to be ranged amongst hard-line Neoplatonists in medieval Islam” (El-Bizri; de Callataÿ 2017, 89).