Since all fevers are caused by abnormal heat rather than natural heat (as previously discussed), we must classify them based on several key factors: the nature of the heat itself, the affected body system, the pattern of heat movement, the underlying cause, the disease mechanism, or the accompanying symptoms. ### Primary Classification by Heat Intensity The first classification is based on the nature of the abnormal heat, which always impairs normal bodily functions by deviating from the natural state. The greater and more intense this heat, the more severe the fever should be considered. For example, a burning fever may be considered more severe than other fevers because its intense heat appears more acrid and corrosive than any other humoral fever. However, when compared to a hectic fever, it is actually less severe, because a hectic fever affects the very substance of vital organs _(see note below)_, while a burning fever affects only the surrounding humors. **Note:** The original states that it affects ‘_the very substance of the heart’_. This could be a reference to the vital faculty in humoral medicine, which includes the heart and arteries, and has a temperament of hot & dry. This would also correspond to the element of fire, the humor of Choler (yellow bile), youth, and the season of summer. ### Classification by Affected Body System Another classification considers which body system is affected. The more vital the affected organ, the more severe the fever becomes. For instance, fevers arising from brain inflammation **_(phrensie)_**, pneumonia **_(peripneumony)_**, lung inflammation, or pleurisy are far more dangerous than those following inflammation of the kidneys **_(reins)_**, spleen, or foot, due to the critical nature of the affected organs. Additionally, fevers can be proportionate or disproportionate to the patient’s constitution. A burning fever is proportionate (and therefore less dangerous) in a hot, dry constitution, in young people during summer, or in hot, dry climates. Conversely, it becomes disproportionate and more dangerous when occurring in elderly patients with cold, moist constitutions during winter in cold, moist regions, as Hippocrates excellently notes in Aphorism 34, Section 2. **Note:** Since fever was associated with hot and dry temperament, vital humor, youth, and summer already. To have a condition like this occur during these times was seen as an imbalance in the humors and particularly dangerous. It’s all about the balances of constitutions and humors. ### Classification by Heat Movement Pattern The third classification considers the pattern of heat movement—essentially how quickly or slowly the condition transitions from one stage to another. Rapid movement occurs when heat passes from thick, dense matter to thin matter, such as when an intermittent fever progresses to a continuous or other putrid fever. Conversely, slow movement occurs when a day-fever **_(ephemera)_** or putrid fever degenerates into a hectic fever, since vital spirits are more easily inflamed than bodily fluids, and fluids more easily than solid organs. Similarly, an uncomplicated continuous fever **_(unputrid synochus)_** , if neglected, easily progresses to a putrid fever, and so forth with other fever types. **Note:** According to the [Colonial North America: Countway Library of Medicine](https://fromthepage.com/harvardlibrary/colonial-north-america-countway-library-of-medicine), there can be a difference between synochus and synocha. **_Synocha_** being an inflammatory fever of short duration that was associated with cold climates and seasons. Whereas, **_Synochus_** was generally associated with typhus or a fever that affected the nervous system. I also came across the term; **_Synochal Fever_** or **_Febricula_** which was said to be a slight transient fever, the similar terminology can make it difficult to distinguish which one is being described in a historical text. ### Classification by Underlying Cause The fourth classification is based on the underlying cause, which can be threefold: evident, internal, or hidden (occult). - **Evident causes** derive from the six non-natural factors: air quality, fasting **_(inanition)_** or overeating **_(repletion)_**, etc. - **Internal causes** stem from fluid accumulations **_(fluxions)_** in the stomach or lungs, obstructions, undigested matter, or similar conditions, putrefaction of the humors etc. - **Hidden causes** **Note:** The above terms can have a few different meanings. **_Inanition_** is more likely the condition that happens from fasting and includes exhaustion, lack of nourishment or vitality. **_Repletion_** is the condition of being overfull. **_Fluxions_** can refer to two different things. In the context of herbal medicine it is a method of creating strong remedies. However, it can also be as simple as referring to our modern equivalent of gastric reflux. The hidden cause may be twofold: external and internal. External causes include contact with electric rays (like torpedo fish), impure sexual relations, the use of harmful and poisonous medications, etc. From these arise epidemic, endemic, sporadic, and pestilential fevers, according to Hippocrates and Galen. The internal cause is difficult to discover because, besides putrefaction, there is a certain poisonous air or breath that is mostly unknown to us. Whether it depends on celestial elements is uncertain, which is why Hippocrates called it _Quid divinum_ “something divine,” as was the sweating sickness in Britain that depopulated not only England but also Germany and France. The fifth classification is based on the matter involved, which consists of either the spirits, the humors, or the solid parts. Hippocrates in the sixth book of his Epidemics, last section, text 19, calls these “containing, contained, and impetuous bodies.” These are the solid parts that cause hectic fevers, both universal and particular. They first attack the substance of the heart, then spread equally to other parts. These fevers primarily possess the substance of some specific part, from which they spread to the heart and to the rest of the solid parts, such as the lungs, diaphragm, stomach, or liver, etc. ### The Contained Bodies These are the four humors that cause problems either in quantity or quality: **In Quantity:** When these humors are more or less inflamed in the heart without putrefaction, resulting in fevers at different stages (pre-peak, peak, and post-peak phases). **Note:** The original terminology for the fever stages is; Epacmastical, Acmastical, and Paracmastical Feavers. **In Quality:** Related to touch, sight, or taste, according to Hippocrates: - **By Touch (Pulse):** Some are judged biting (mordant), others mild and temperate in comparison; others appear moist like bilious fevers, such as continuous tertian fevers or burning fevers. All of these are biting (mordant), especially during the active phase of the disease and before the crisis. The mild ones include the true daily (diary) fever, which ends with sweating or moisture, and non-putrid continuous fevers (unputred Synochus). **Note:** After this there is mention of another type of fever, but the reference text does not include it as it’s in a non-Latin script. However, it is described as a moist fever that is mild and temperate. **By Sight:** Red fevers (like non-putrid continuous fever from overheated blood), white ones (like daily fevers)(quotidian), livid ones (like quartan, fainting (syncopal), or pestilential fevers), and others that are dry and horrible to look at, like wasting hectic fevers of the second or third degree. **By Taste:** Some are sweet (from natural phlegm and many blood-based fevers that retain sweetness even after putrefaction), others are bitter (bilious fevers), and others are salty (from salt phlegm and winter (hybernal) causes, or winter burning fever). ### Characteristics of Fevers Some fevers are long, others short; some occur during the day, others at night; some follow a pattern, others are irregular; some are periodic, others erratic—all depending on the patient’s condition, the quality of the diseased matter, its quantity, and movement. ### Classification by Symptoms The sixth classification of fevers is based on their symptoms, particularly when a body part is affected by inflammation. These fevers are always continuous, whether blood, bile, or phlegm predominates: - If **blood** predominates: the fever is called inflammatory (Phlegmonodes). - If **bile** predominates: it’s called erysipelatous and typhoid (typhodes), or burning fever. These fevers also receive names based on the affected part: - **Liver**: Hepatic fever (Hepatica) - **Spleen**: Splenic fever (Splenica) - **Bladder**: Cystic fever (Cystica) - **Throat**: Throat fever (Cynanchica) - **Head**: Brain fever, lethargic fever, comatose fever (Phrenitica) (Lethargica) (Comatosa) - **Lungs**: Pneumonic fever (Pneumonica) - **Side**: Pleuritic fever (Pleuritica) - **Diaphragm**: Diaphragmatic fever (Diaphragmatica) - **Womb**: Hysteric fever (Hysterica) - **Stomach**: Stomach fever, etc. (Stomachica)