How can one reconcile the noble verse: (Have they not traveled through the land, and have hearts by which to reason?) and the Prophet’s (peace be upon him) saying: (Indeed, there is in the body a piece of flesh which, if it is sound, the whole body is sound, and if it is corrupt, the whole body is corrupt. Indeed, it is the heart), knowing that the organ responsible for thinking is the brain, and that the heart mentioned in the Hadith is a physical organ?

The linguistic meaning of 'Aql' (intellect/reason) is summarized as connection, prevention, and confinement. Terminologically, philosophers, theologians, and jurists have differed in its definition, but they have agreed that it is an innate faculty through which knowledge is perceived, or a deeply rooted characteristic that enables its possessor to grasp perceptions, or a power prepared to accept knowledge.

Revelation has not specified a physical location for the intellect; therefore, the intellect has no material existence, but rather it is an immaterial attribute. The revelatory texts that refer to the heart as an instrument of understanding are metaphorical, not literal, expressing the comprehension and adherence to truth, and they used what the Arabs were accustomed to, attributing emotions to the heart.

Scholars have differed in their opinions regarding the location of the intellect. Some said it is in the heart, citing verses such as: "Have they not traveled through the land, and have hearts by which to reason?" [Qur’an 22:46] and the Hadith (Indeed, there is a piece of flesh in the body...). Others said it is in the brain, citing the impairment of intellect when the brain is impaired, and this was attributed to Imam Ahmad. As for Ibn Taymiyyah, he stated that the intellect subsists in the human self and is connected to both the heart and the brain: the principle of thought is in the brain, and the principle of will is in the heart.

The closest opinion is that the intellect is an immaterial innate faculty related to the self, and that the reference to the heart or the brain in the texts was for the location that plays a physiological cognitive role affecting the intellect, without the intellect itself being material. Modern science suggests that the brain and the nervous system are the seat of physiological cognition.