  (b) Regarding Avicenna: While Avicennian notions can arguably be found in Maimonides, his view of the thinker is complicated. In a letter to Ibn Tibbon, Maimonides clearly states that Avicenna's philosophy is of lesser value than al-Farabi's. That said, even in that context Maimonides characterizes Avicenna’s ideas as subtle and exacting, and as worthy of study.[5]