Refuting the Claim That a Person’s Temperament Never Changes from Birth Until Death

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In the Name of Allah, the Most Compassionate, the Most Merciful. Praise be to Allah, Lord of the worlds, and may blessings and peace be upon the Messenger of Allah.

Some people believe that a person's temperament (mizāj) remains exactly as it was at birth until old age and death. Thus, if a person is born with a balanced temperament, or a sanguine, phlegmatic, yellow bile-dominant, or black bile-dominant temperament, they assume that this temperament remains unchanged throughout life.

I say that this is a ruling issued without knowledge. It contradicts the fundamental principles of medicine upon which physicians have reached consensus, and it is also contrary to what is plainly observed, since the temperaments of most people change as they grow older. Ibn al-Nafīs¹ stated in Al-Mūjaz fī al-Ṭibb:

"Young adults are the most moderate. Children are equal to them in hotness, but they are wetter; therefore, their hotness is gentler, whereas the hotness of young adults is more intense. Middle-aged people and the elderly are cold and dry, while the elderly are wetter because of adventitious residual wetness."

The author, may Allah have mercy upon him, said:

"Young adults are the most moderate."

Explanation:
That is, they are the most moderate with respect to wetness when compared with children, middle-aged adults, and the elderly. This is because children possess abundant and excessive wetness, whereas after the stage of youth, the body's wetnes gradually diminishes and dries.

The author, may Allah have mercy upon him, said:

"Children are equal to them in hotness."

Explanation:
That is, they are equal in innate hotness—meaning the strength of its action rather than its quantity. The innate hotness present within a child's innate wetness is greater in quantity than the innate hotness of a young adult because the child possesses a greater amount of innate wetness, which serves as its substrate.

The author, may Allah have mercy upon him, said:

"But they are wetter."

Explanation:
That is, the bodies of children are wetter than those of young adults because they are in the stage of growth. This is confirmed by observation and experience, as evidenced by the softness of their bones and nerves.

The author, may Allah have mercy upon him, said:

"Therefore, their hotness is gentler, whereas the hotness of young adults is more intense."

Explanation:
That is, the heat of young adults is more intense than that of children because children possess greater wetness, whereas young adults have less wetness. As a person grows older, the body's wetness naturally decreases and becomes drier.

Explanation:
That is, the heat of young adults is more intense than that of children because children possess greater wetness, whereas young adults have less wetness. As a person grows older, the body's wetness naturally diminishes and dries.

The author, may Allah have mercy upon him, said:

"Middle-aged people and the elderly are cold and dry."

Explanation:
That is, they are cold because of the decline in innate hotness. As innate hotness diminishes, so does its substrate—namely, the innate hotness. Consequently, coldness and dryness come to predominate, and their bodies become dry as a result of the continual dissolution and depletion of their wetness. This is evident from the increased hardness of their bones and the dryness and roughness of their skin.⁴

The author, may Allah have mercy upon him, said:

"The elderly are wetter because of adventitious residual wetness."

Explanation:
That is, the elderly possess greater adventitious residual wetness because, as digestion weakens with age, food is no longer transformed as it should be. As a result, excess adventitious wetness⁵ accumulates in the body, causing the organs to become wet—not by becoming intrinsically wet, as in children, but merely by surface dampness. The wetness of a child resembles that of a fresh, tender green branch, whereas the wetness of an elderly person resembles that of withered wood—dried and lifeless. This adventitious wetness actually increases the dryness of the primary organs⁶ because, when it accumulates externally, it prevents them from being nourished by proper nutrition. Since this moisture itself is merely waste, it is unsuitable for nourishing the organs, which therefore become drier through lack of nourishment. As for the middle-aged adult, this adventitious wetness does not yet develop because digestion has not weakened sufficiently to produce that condition. Were it not for this moisture in the elderly, their dryness would be far greater than that of middle-aged adults.

Ibn al-Nafīs stated in Al-Mūjaz fī al-Ṭibb:

"The management of food is as follows: Whenever we wish to preserve a state of health as it is, we administer that which is similar to it in quality. But if we wish to improve it, we administer its opposite."

The author, may Allah have mercy upon him, said:

"The management of food: Whenever we wish to preserve a state of health as it is..."

Explanation:
That is, when health is complete and perfect, with no deficiency whatsoever, and the individual possesses a balanced temperament between hotness and coldness, and between wetness and dryness.

The author, may Allah have mercy upon him, said:

"We administer that which is similar to it in quality."

Explanation:
That is, to preserve the health of the body, we provide foods whose qualities of hotness, coldness, wetness, and dryness correspond to the moderate temperament of a healthy body.

The author, may Allah have mercy upon him, said:

"But if we wish to improve it, we administer its opposite."

Explanation:
That is, when health is not yet complete—as in the case of a person with a sanguine, phlegmatic, yellow bile-dominant, or black bile-dominant temperament—we administer foods and drinks possessing the opposite qualities. For example, a person whose temperament is healthy yet excessively hot is given cooling, balancing foods and beverages to bring the temperament gradually toward perfect moderation between hotness and coldness, and between wetness and dryness. The same principle applies to temperaments that are excessively cold, wet, or dry.

Ibn al-Nafīs also stated in Al-Mūjaz fī al-Ṭibb:

"The food of the yellow bile-dominant should be cooling and wettening; the food of the sanguine should be cooling and restraining; the food of the phlegmatic should be warming and attenuating; and the food of the black bile-dominant should be warming and wettening."

The author, may Allah have mercy upon him, said:

"The food of the yellow bile-dominant should be cooling and wettening."

Explanation:
That is, one who wishes to preserve health and possesses a hot and dry  temperament should avoid foods that are hot and dry, and instead consume foods that are cold and  wet, characteristic of the phlegmatic temperament, until moderation is restored.

The author, may Allah have mercy upon him, said:

"The food of the sanguine should be cooling and restraining."

Explanation:
That is, a person with a hot and wet (sanguine) temperament should avoid hot and wet foods and instead consume foods that are cold and dry, characteristic of the black bile-dominant temperament, until balance is achieved.

The author, may Allah have mercy upon him, said:

"The food of the phlegmatic should be warming and attenuating."

Explanation:
That is, a person with a cold and wet (phlegmatic) temperament should avoid cold and wet foods and instead consume hot and dry foods, characteristic of the yellow bike-dominant temperament, until moderation is restored.

The author, may Allah have mercy upon him, said:

"The food of the black bile-dominant should be warming and wettening."

Explanation:
That is, a person with a cold and dry  temperament should avoid cold and dry foods and instead consume hot and wet foods, characteristic of the sanguine temperament, until moderation is achieved. This dietary principle for restoring moderation is one of the established foundations unanimously accepted by doctors of humoral medicine.

Conclusion

From this, it is understood that the temperament of a child is hot and wet. As the child progresses into youth, the temperament becomes hot and dry. Upon reaching middle age, coldness and dryness begin to develop, and in old age these qualities become even more pronounced. This is an observable reality experienced by the majority of people.

Accordingly, as stated in the classical medical texts, bodies that have deviated from moderation should be restored to balance through appropriate foods and medicines. For example, a person whose temperament is cold and dry should be treated with hot and wet foods and medicines until moderation between hotness and coldness, and between wetness and dryness, is re-established. The same principle applies to the remaining temperaments.

Whoever issues the ruling that a person's temperament remains exactly as it was at birth throughout life—on the grounds that the person's blood type does not change—and therefore claims that someone born with a hot and wet (sanguine) temperament remains so until death, or that one born hot and dry (yellow bile-dominant), cold and wet (phlegmatic), or cold and dry (black bile-dominant) remains in that same temperament for life, has issued a ruling without knowledge and has contradicted the consensus of doctors.

A person's temperament changes according to age, regimen, habit, and other factors. Such a ruling misleads people into believing that they remain moderate—or remain sanguine, phlegmatic, yellow bile-dominant, or black bile-dominant—for their entire lives simply because they were born that way. This claim is false and has no foundation in medicine. For example, a person born with a hot and wet (sanguine) temperament may now be an elderly individual in whom coldness and dryness predominate. If such a person mistakenly believes they are still sanguine and therefore consumes cold and dry foods and medicines because of this erroneous ruling, they will only harm themselves.

Indeed, I am astonished by the abundance of anomalous rulings in humoral medicine issued by people without knowledge—based merely on personal opinion and inclination, without regard for the established principles of either the Sacred Law or medicine. Such people have gone astray and have led astray those who relied upon their opinions.

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Footnotes

(1) Al-Ḥāfiẓ al-Suyūṭī (849–911 AH), who was born in Cairo, mentioned Ibn al-Nafīs in his book Ḥusn al-Muḥāḍarah fī Akhbār Miṣr wa al-Qāhirah, saying:

"Ibn al-Nafīs, the eminent scholar ʿAlāʾ al-Dīn ʿAlī ibn Abī al-Ḥazm al-Qurashī al-Dimashqī, the leading physician of the Egyptian lands, author of Al-Mūjaz, the commentary on Al-Qānūn, and other works. He was among those who attained the highest mastery of medicine, distinguished by exceptional intelligence, a keen mind, and proficiency in jurisprudence (fiqh), legal theory (uṣūl), ḥadīth, Arabic, and logic."

Imām al-Yāfiʿī (c. 696–769 AH) also mentioned him in Mirʾāt al-Janān, stating:

"In the year 687 AH, Ibn al-Nafīs, the eminent scholar ʿAlāʾ al-Dīn ʿAlī ibn Abī al-Ḥazm al-Qurashī al-Dimashqī, the leading physician of the Egyptian lands and author of numerous works, passed away. He was among those who attained the highest mastery of medicine, distinguished by exceptional intelligence, a keen mind, and proficiency in jurisprudence, legal theory, ḥadīth, Arabic, and logic."

(2) Innate Hotness (al-Ḥarārah al-Gharīziyyah): In classical medical terminology, it is a subtle, airy, warm essence that possesses neither sharpness, stinging, burning, putrefaction, nor corruption. It is infused into the body when the soul is infused into it and departs when the soul departs.

(3) Innate Wetness (al-Ruṭūbah al-Gharīziyyah): In classical medical terminology, it is a moist, flowing substance. Its relationship to innate heat is like that of oil to a lamp.

(4) Excessive Dryness (al-Qashaf and al-Qashafah): In classical medical terminology, these terms refer to extreme dryness, sun-induced burning and roughness of the skin. Hence, a mutaqashif is a person who neglects cleanliness and comfort.

(5) Adventitious Residual Wetness (al-Ruṭūbah al-Gharībah al-Bālah): In classical medical terminology, this is the wetness that accumulates in the body when innate hotness weakens and the digestive faculty is unable to transform food into a substance resembling the body's own essence. This hotness does not benefit the body; rather, it contributes only to increased dryness in the primary organs because it is extraneous to their essential substance.

(6) Primary Organs (al-Aʿḍāʾ al-Aṣliyyah): In classical medical terminology, these are the bones, nerves, and blood vessels. It is also said that the primary organs are those that originate from semen during embryonic development.