Sedentary culture is the goal of civilization. It means the end of its lifespan and brings about its corruption.
Ibn KhaldunGeometry enlightens the intellect and sets one's mind right. All of its proofs are very clear and orderly. It is hardly possible for errors to enter into geometrical reasoning, because it is well arranged and orderly. Thus, the mind that constantly applies itself to geometry is not likely to fall into error. In this convenient way, the person who knows geometry acquires intelligence.
Ibn KhaldunThroughout history many nations have suffered a physical defeat, but that has never marked the end of a nation. But when a nation has become the victim of a psychological defeat, then that marks the end of a nation.
Ibn KhaldunThe term of life of a dynasty does not normally exceed three generations. For in the first generation are still preserved the characteristic features of rough, uncivilized rural life, such as hard conditions of life, courage, ferocity, and partnership in authority. Therefore the strength of the 'Asabiya is maintained.
Ibn Khaldun