Why is the heart (qalb) referred to as the intellect (aql) in the Holy Qur’an?

Among the functions of the heart are jurisprudence (understanding) and intellect. The term "intellect" encompasses the instinct by which one distinguishes things. The intellect is inherent in the human self and is connected to the heart. As for the brain, it is the origin of thought and contemplation, while the heart is the origin of will. Both have a role in the intellect.

Modern science has proven that the prefrontal cortex (forehead) is the center of decision-making and is responsible for lying and error, which aligns with the Almighty’s saying: (A lying, sinning forelock) (Al-Alaq: 16). And that the forelock in animals is the center of control, as in His Almighty’s saying: (There is no creature but that He holds its forelock) (Hud: 56).