The sciences of only one nation, the Greeks, have come down to us, because they were translated through Al-Ma'mun's efforts. He was successful in this direction because he had many translators at his disposal and spent much money in this connection.
Ibn KhaldunTherefore, the Negro nation are, as a rule, submissive to slavery, because [Negroes] have little [that is essentially] human and have attributes that are quite similar to those of dumb animals, as we have stated.
Ibn KhaldunAt the beginning of a dynasty, taxation yields a large revenue from small assessments. At the end of the dynasty, taxation yields a small revenue from large assessments.
Ibn KhaldunWhen 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.
Ibn KhaldunThe easiest method of acquiring the habit of scholarship is through acquiring the ability to express oneself clearly in discussing and disputing scholarly problems. This is what clarifies their import and makes them understandable. Some students spend most of their lives attending scholarly sessions. Still, one finds them silent. They do not talk and do not discuss matters. More than is necessary, they are concerned with memorizing. Thus, they do not obtain much of a habit in the practice of scholarship and scholarly instruction.
Ibn Khaldun