Isagoge

But a neutral quality consists of three modes: as if infirmity and health convene in one body from different members, as is the case in the body of a blind man or a lame man, or in the body of an old man, to whom not even one member remains that does not become evil and suffer. Or if the body of a man is healthy at some hours but infirm at others, as in those who are infirm in summer and healthy in winter. Those who are of a colder nature are infirm in winter and healthy in summer. And those who have a moist nature are infirm in childhood, but are healed in youth and old age; those who are dry are healthy in childhood, but infirm in youth and old age. In the three things mentioned—health, infirmity, and neutrality—they are found: either in the body in which each of the three qualities is found, or in the cause that makes, governs, and preserves them, or in the significations signifying them.

Concerning the modes of occasions.

There are two genera of occasion: one is natural, and the other is outside the course of nature. Natural occasions either produce health or preserve it. Preserving occasions pertain to health, while the producing ones pertain to repelling infirmity. Non-natural occasions, or those that proceed beyond nature, some pertain to infirmity, some to the neutral. But sick occasions produce infirmity, and the things preserving the same infirmities. Those, however, that pertain to neither health nor infirmity constitute the neutral and preserve it.

Concerning the occasions of health and infirmity.

There are six modes of all occasions having society with health and infirmity, one of which is air, which surrounds the human body; food and drink; motion and rest; sleep and vigils; depletion and repletion; and the accidents of the mind. All of these, if they are with decent moderation—and in quantity, quality, time, work, and order—preserve health from accidents. But if anything is done against this, infirmities happen and remain.

The modes of occasions making infirmity are three.

For some are called privative, which happen to the body exteriorly, such as heat and cold. There are also accidents that move intrinsically in the body, such as repletion and depletion. There are also others that are called augmentative, which, while the infirmity is present, are there, and with them departing, the infirmity departs, such as putrefaction in fevers.

Concerning the diversity of sicknesses.

According to another division, there are two modes of sicknesses: commonly or properly. Those that happen commonly either happen accidentally or necessarily. Accidentally, such as striking, burning, biting, deception, and other harmful things. Necessarily, such as the others mentioned above, which, as has been said, are associated with health and infirmity. Those that are properly sicknesses are either in similar members and preserve the sickness, or in official ones, or in continuous division.

Concerning the modes of diseases proceeding from heat.

There are five modes of diseases proceeding from heat. The first happens from the commotion of the spirit or from the commotion of the body: from the commotion of the spirit, such as anger; of the body, such as labor or pride. The second, as is the concurrence of visible heat with effect, such as hypantasis exposure to the sun. The third, from heat arriving to the body with power when it receives heat from eating sharp things. The fourth happens from the interclusion of the pores, such as from the coldness of winter. The fifth happens from the putrefaction of humors, as in fevers.

Concerning the causes of cold diseases.

There are eight occasions for cold diseases. The first occasion is the encounter of visible cold with effect, such as the coldness of snow. The second, such as the coldness of opium arriving strongly to the human body. The third, from the abundance of foods arriving to the body, and filling it, and extinguishing the natural heat. The fourth, from the scarcity of food, whence the natural heat is extinguished. The fifth, from the abundance of cold, such as cold humor closing the pores, whence natural heat is diminished.

The sixth, from the dissolution and opening of the body to dissolve and evacuate the natural heat. The seventh, from the commotion and excessive exercise, whence much dissolution of humors is made and evacuation and sweating, whence the body is attenuated. The eighth happens from rest and much idleness.

Concerning the causes of dry diseases.

There are four occasions for dry diseases. The first occasion is the encounter of alien dryness, visible and manifest, with effect, such as the dryness of poison. The second, from the arrival of a dry thing in the body with strength, such as vinegar, salt, or mustard. The third is the scarcity of food and drink. The fourth is excessive commotion and exercise.

Concerning the causes of moist diseases.

There are four occasions for moist diseases. The first, such as the encounter of a thing bringing moisture with effect, such as a bath. The second, such as the ingress of a thing bringing moisture with virtue into the body, such as fresh fish. The third, such as the excess of food and drink. The fourth, such as rest and idleness.

Concerning the modes of diseases from unnatural malice.

There are four modes of diseases from unnatural malice with some humor occurring to infirm places: the first is the virtue of the member pushing, and the weakness of the member sustaining; the second is the multitude of humors; the third is the weakness of the nourishing virtue; the fourth is the wideness of the way of the pores.

Concerning the malice of sickness.

The malice of sickness enters and supervenes in a similar natural member in five ways: either it happens in the maternal womb, or at the time of birth, or when it is constricted by a bandage, or from bad nourishment, or from some infirmity arriving at the aforementioned times or afterwards. If at the time of conception in the womb some member of the infant is weakened, it becomes an abundance of sperm, or from the scarcity and indigence of the convenient quality of sperm, such as if it were thick and fatty, or watery and thin. When an infant is born and some member in him is weakened if he has been born not by an equal but by an evil exit, such as supine, or bent over the knees. When, therefore, the bandage is tightened by inconvenient constriction, it is doubled and weakened. When, however, he is weakened by sucking or taking inconvenient nourishment. At these times or afterwards, when sickness happens, the malice of sickness supervenes in the similar member from the incision of any nerve. And if it has suffered from some accident, either weakness, a wound, or an aposteme.

Concerning the sickness of similar members.

Sickness enters a similar natural member in seven ways: either from the midwife if she had guilt when she held the infant, or if she allowed him to walk before the appropriate time; or from the physician if he ignorantly placed and constricted fractured and bruised members; or from the infirm person if he moved them before they were positioned by the physician before they could solidify and be firm; from a fracture, such as if a vertebra above the muscle, which is in the thigh, is twisted against its nature; or from a concussion, such as if the nose is compressed and it happens that he becomes snub-nosed; or from bad humor that happens to the leprous, or from the purity of humor happening to the consumptive.

Concerning the modes of the constriction of the pores.

The constriction of the pores happens in three modes or occasions: either from the constriction that causes attenuation, or from fleshiness, or from coarctation original: "coartatōne". Constriction, however, happens either from the excess of the retaining virtue, or the weakness of the expelling virtue, or from the abundance of cold, or from abundant constriction compressing some part of the place, such as often happens from a tight binding, or from the abundance of dryness. From fleshiness, the pores are constricted, such as if some aposteme happens and fleshiness is made, or if a wound happens earlier. From coarctation, however, when something falls into the pores, such as humor, or a stone, or coagulated blood, or something hiding in them.