When pathogenic factors attack the body, healthy qi in the body naturally fights against them.

当致病因素攻击身体时，体内的正气会与它们作斗争。

Deficiency and excess are two principles for differentiating the states of pathogenic factors and healthy qi. Deficiency means insufficiency of healthy qi and excess means exuberance of pathogenic factors.

虚证和实证是区分邪气和正气状态的两个原则。虚指正气不足，实指邪气盛实。

Since it involves the location, cause and nature of the disease, and the relation between pathogenic factors and healthy qi, syndrome can comprehensively and accurately reveal the nature of the disease.

证包括李病变的部位、原因、性质，以及邪正关系，证可以全面、准确地揭示疾病的本质。

Pathologically TCM considers that the imbalance between yin and yang is one of the basic pathogenesis of disease. The occurrence and development of a disease are related to the conditions of both the healthy qi and pathogenic factors.

病理上，中医认为阴阳失衡是疾病的基本发病机制之一。疾病的发生和发展既与正气有关， 也与致病因素有关。