Sources of his philosophy ; his theory of being ; metaphysics of emanation ; nature and man ; theory of knowledge ; his theory of politics, society and morality ; Al-Farabi School: his impact on Ibn-Sina, Sadr ad-din Shirazi, Ibn-Baja, Ibn-Tofail, Ibn-Rushd, Ibn-al-Sayed Al-Batleosee ; his impact on the Christian European philosophy.