According to Arabo-Islamic physicians, the overall functioning of the body demonstrates the reciprocity between the mixture of the humours on one side and the psychological events on the other. This is the reason that primary qualities (in other words, the mixture of hot and cold on one side, and dry and moist on the other), have a strong influence on an individual’s moral character: if the mixture of the humours is globally hot, the person will get angry quickly; but if it is globally cold, he will be fearful and slow by nature. Conversely, the state of the soul has an impact on the bodily balance: psychological affections (al-ʾaḥdāth al-nafsānīya), such as anger, sadness, worry, fear, and pleasure, belong to the eight ‘non-natural’ factors that can be acted upon to modify the mixture of the humours...
Left: A 16th-century Persian miniature dipicting Ibn Sina (Avicenna) at the bedside of a patient suffering from love-sickness (ʿishq). According to Arabo-Islamic physicians, the overall functioning of the body demonstrated the reciprocity between the mixture of the humours on one side and psychological events on the other.