Geometry enlightens the ...

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.
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 Ibn Khaldun

Quotes from the same author

The 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.
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 Ibn Khaldun
If the soul is impartial in receiving information, it devotes to that information the share of critical investigation the information deserves, and its truth or untruth thus becomes clear. However, if the soul is infected with partisanship for a particular opinion or sect, it accepts without a moment's hesitation the information that is agreeable to it. Prejudice and partisanship obscure the critical faculty and preclude critical investigation. The results is that falsehoods are accepted and transmitted.
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 Ibn Khaldun
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.
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 Ibn Khaldun
Man is essentially ignorant, and becomes learned through acquiring knowledge.
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 Ibn Khaldun
At 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.
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 Ibn Khaldun