When incentive to acquire and obtain property is gone, people no longer make efforts to acquire any... Those who infringe upon property rights commit an injustice... If this occurs repeatedly, all incentives to cultural enterprise are destroyed and they cease utterly to make an effort. This leads to destruction and ruin of civilization.

Man is essentially ignorant, and becomes learned through acquiring knowledge.

He who finds a new path is a pathfinder, even if the trail has to be found again by others; and he who walks far ahead of his contemporaries is a leader, even though centuries pass before he is recognized as such.

Man is the child of customs, not the child of his ancestors.

Geometry 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.

Throughout 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.

Beyond [known peoples of black West Africa] to the south there is no civilization in the proper sense. There are only humans who are closer to dumb animals than to rational beings. They live in thickets and caves, and eat herbs and unprepared grain. They frequently eat each other. They cannot be considered human beings.