Ibn Khaldun, though a conservative in certain aspects of his belief, was nevertheless dismayed by the negative attitudes towards learning among the Muslims. He writes: When the Muslims conquered Persia and came upon an indescribably large number of books and scientific papers, Sa'd bin Abi Waqqas wrote to Umar bin al-Khattab asking him for permission to take them and distribute them as booty among the Muslims. On that occasion, Umar wrote him: 'Throw them in the water. If what they contain is right guidance, God has given us better guidance. If it is error, God has protected us against it.