Coan作家最具历史意义的理论方案是身体四种体液的学说：血液，痰，黑胆汁和黄胆汁（或有时是血清）。健康被定义为四种幽默的平衡。疾病被定义为幽默的不平衡。当发生不平衡时，医生可能会进行干预，进行矫正，使身体恢复平衡。例如，如果个体过于充满痰（使她出现冷漠或昏昏欲睡），那么必须对抗痰。柑橘类水果被认为是反作用剂。因此，如果一个人感到昏昏欲睡，增加一个人的柑橘摄入量将重新创造平衡。事实上，治疗通常是有效的。现代人可能会通过归因于对维生素C，磷和天然糖的影响来描述治疗方法。这个例子说明了希波克拉底医生在这方面的范围：类似于草药营养师和私人教练的现代角色之间的交叉。尽管如此，由四种幽默理论决定的治疗效果似乎足以使这一理论延伸到十九世纪（以各种形式）。
加拿大多伦多大学医学Essay代写：四种因素
The most historically prominent theoretical scheme of the Coan writers was the doctrine of the four humors of the body: blood, phlegm, black bile, and yellow bile (or sometimes serum). Health was defined as the balance of the four humors. Disease was defined as the imbalance of the humors. When imbalance occurred, then the physician might intervene by making a correction to bring the body back into balance. For example, if the individual were too full of phlegm (making her phlegmatic or lethargic), then the phlegm must be countered. Citrus fruit was thought to be a counter-acting agent. Thus, if one feels lethargic, increasing one’s citrus intake will re-create balance. The treatment is, in fact, generally effective. Moderns might describe the therapy differently by ascribing the effect to vitamin-C, phosphorus, and natural sugar. This example illustrates the scope of the Hippocratic physician in this context: something like a cross between the modern roles of an herbalist dietician and a personal trainer. Nonetheless, the cures that were dictated by the four humor theory seemed to work well enough for this theory to extend to the nineteenth century (in various guises).