It should be known that at the beginning of a dynasty, taxation yields a large revenue from small assessments. At the end of the dynasty, taxation yi… - Ibn Khaldun

Thus, the founders of grammar were Sîbawayh and, after him, al-Fârisî and Az-Zajjâj. All of them were of non-Arab (Persian) descent. They were brought up in the Arabic language and acquired the knowledge of it through their upbringing and through contact with Arabs. They invented the rules of (grammar) and made it into a discipline (in its own right) for later (generations to use). Most of the ḥadîth scholars who preserved traditions for the Muslims also were Persians, or Persian in language and upbringing, because the discipline was widely cultivated in the 'Irâq and the regions beyond. Furthermore all the scholars who worked in the science of the principles of jurisprudence were Persians. The same applies to speculative theologians and to most Qur'ân commentators. Only the Persians engaged in the task of preserving knowledge and writing systematic scholarly works. Thus, the truth of the following statement by the Prophet becomes apparent: 'If scholarship hung suspended in the highest parts of heaven, the Persians would attain it.'

Indeed, you should not desire to weigh with the intellect the issues of Tawhīd and the Hereafter; the reality of Prophethood; the reality of divine attributes and every other thing beyond the scope of the intellect, for such a desire is futile. An example of this would be a man who has a scale used for weighing gold suddenly desiring to weigh mountains with it! This does not mean that the scale is wrong in its measures; rather, the intellect has a limit it cannot surpass and a boundary it cannot transcend.

Eventually, Aristotle appeared among the Greeks. He improved the methods of logic and systematized its problems and details. He assigned to logic its proper place as the first philosophical discipline and the introduction to philosophy. Therefore he is called the First Teacher.