In the changing seasons, the body’s inner balance shifts in subtle ways. During autumn, bile naturally increases, soon followed by phlegm. Because these humors are released in their proper time, one need not fear eating a variety of foods during this period. When spring arrives, phlegm predominates, and then wind and bile may follow. If any disorder of the humors arises in this season, it is often mild; fever, when it occurs, is usually curable and free from severe complications. However, if a disorder is recognized in its early stages and is not properly addressed, it is considered difficult to cure. The complications of severe fever can be grave: digestion weakens, urination becomes excessive, and the appetite fades away. Hunger is absent, digestion is impaired, and the fever takes on a distinct appearance. Its intensity grows, bringing increased thirst, delirium, labored breathing, and dizziness. The urge to pass waste, or the disturbance of that urge, signals the fever’s maturation. If this process does not reverse, fasting for seven nights is prescribed as a path to resolution. Fever itself is known to manifest in five primary forms, determined by the nature of bodily wastes, the time of onset, and the individual’s strength or weakness. Most often, however, fever arises from the derangement of all three humors—wind, bile, and phlegm. These fevers are categorized as continuous, constant, recurring every other day, every third day, or every fourth day. They are carried within the body by the humors, urine, and feces, and are widespread due to the presence of these wastes. From the very start, these fevers heat the entire body, their intensity increasing equally throughout. They are strong and heavy, residing in the vital fluids without distinction. Such fever, constant and unopposed, is particularly hard to endure; the heat or the disturbed humors can quickly devastate the body. Whether the vital fluids and tissues are pure or impure, wind, bile, and phlegm can each cause fever, typically lasting seven, six, or twelve days respectively. The boundary for both recovery and destruction is generally observed, following the opinions of revered sages like Agnivesha and the tradition of Harita. The seventh day—sometimes doubled—as well as the ninth and eleventh, are considered critical boundaries for the three doshas, marking possible turning points for either recovery or decline. Yet, due to impurity, fever may linger for a long time, especially in those who are emaciated, already afflicted by disease, or who indulge in improper diet and habits. Even a minor defect, if strengthened by impurity or other causes, can become antagonistic and unpredictable, waxing and waning irregularly. With such disturbance, fever arises, its course marked by irregular increases and decreases, as the dosha acts according to its own timing. The fever may subside when opposed by sufficient strength or the reduction of the offending dosha. At that point, the subtle fever merges into the fluids and tissues. This merging, however, brings emaciation, discoloration, dullness, and similar conditions, because the channels carrying fluids are altered and impaired. The defect does not quickly spread throughout the body in virtuous individuals, but in others, the opposite is true. Some fevers are irregular, with unpredictable onset, often arising at night. When the dosha resides in the blood, it generally produces continuous fever. At the junction of day and night, fever may appear once, then again on another day, affecting the channels that carry flesh and fat in turn. There are many specific forms of fever: one arises from bile and wind in the head, another from phlegm and bile in the trika region, and yet another from wind and phlegm in the back, typically manifesting after a day. The fourth type is found in the impurities, fat, marrow, or bone, while another type affects only the marrow and bone. Phlegm can cause a twofold fever, sometimes beginning in the calves and first arising from wind in the head. When it reaches the bone and marrow, it behaves as the reverse of the fourth type. There is also a threefold fever, which persists for three days and then releases for one day, its pattern shaped by the doshas and other factors. When reversal does not occur, fasting for seven nights is again prescribed. Fever affects the mind as much as the body, influencing actions during its course and at other times. The fourth type of fever, arising from deep-seated behavior in the tissues, from the combination and equal increase of the doshas, is especially difficult to treat. In subtle fevers, the dosha travels slowly through the blood and other channels, affecting the body over a long period. It causes burning and other symptoms, and when its course is interrupted by effort, fever with burning is observed. Such fevers are uneven, with difficult onsets, often following the course of the night, each stage slower and weaker than the last. Over time, the disorder acquires corresponding tastes and qualities, and when provoked, it may burn fiercely, sometimes after a long delay. Just as a seed, once planted and watered, does not await a specific time to sprout, so too does the seed of disorder act without waiting. Likewise, poison, when given momentum, quickly exerts its force upon the body; so too does disorder, empowered by time, become agitated and active. Thus, fevers arise—irregular and persistent—causing agitation, heaviness, dejection, collapse of the limbs, and stretching of the body. Loss of appetite, vomiting, and breathlessness are common to all fevers, as are spitting blood, thirst, dryness, heat, and painful effort. In those with blood involvement, burning, redness, confusion, delirium, and incoherent speech may appear, along with thirst, fatigue, altered complexion, internal burning, dizziness, and darkness before the eyes. When the disorder is in the flesh or fat, there may be a foul smell, twitching of the limbs, sweating, excessive thirst, vomiting, and sometimes a foul odor or endurance of symptoms. Delirium, fatigue, loss of appetite, pain in the bones, and a sensation of splitting may occur, along with activation of the disorder, sleeplessness, breathlessness, spasms, and groaning. When fever reaches the marrow, it causes internal burning, external coldness, breathlessness, and hiccups, as well as darkness of vision, stabbing pains in vital spots, and stiffness of the genitals. If the disorder reaches the semen, death may result; the five fever types that follow are increasingly difficult to cure in reverse order. When phlegm is involved, the limbs may feel as if smeared with heaviness; in milder fevers, delirium may appear along with coldness and a sensation of being covered or enveloped. Thus, the ancient sages described the many forms and courses of fever, their symptoms, and their challenges, guiding all toward proper understanding and care.