素问·刺志论 Treatise on the Purport of Needling
黄帝问曰：愿闻虚实之要。歧伯对曰：气实形实，气虚形虚，此其常也，反此者病。谷盛气盛，谷虚气虚，此其常也，反此者病。脉实血实，脉虚血虚，此其常也，反此者病。
帝曰：如何而反。歧伯曰：气虚身热，此谓反也。谷入多而气少，此谓反也。谷不入而气多，此谓反也。脉盛血少，此谓反也。脉少血多，此谓反也。
气盛身寒，得之伤寒。气虚身热，得之伤暑。谷入多而气少者，得之有所脱血湿居下也。谷入少而气多者，邪在胃及与肺也。脉小血多者，饮中热也。脉大血少者，脉有风气，水浆不入，此之谓也.
夫实者，气入也。虚者，气出也。气实者，热也。气虚者，寒也。入实者，左手开针空也。入虚者，左手闭针空也。
Huangdi asked: I wish to hear the essentials of deficiency and excess. Qibo replied: When the qi is in excess, the body form is correspondingly full; when the qi is deficient, the body form is correspondingly weak — this is the normal pattern, and when it is otherwise, there is disease. When food intake is abundant, the qi is correspondingly abundant; when food intake is scant, the qi is correspondingly scant — this is the normal pattern, and when it is otherwise, there is disease. When the pulse is full, the blood is correspondingly full; when the pulse is deficient, the blood is correspondingly scant — this is the normal pattern, and when it is otherwise, there is disease.
Huangdi said: What constitutes 'otherwise'? Qibo said: When the qi is deficient yet the body is hot, this is called 'otherwise.' When food intake is abundant yet the qi is scant, this is called 'otherwise.' When food does not enter yet the qi is abundant, this is called 'otherwise.' When the pulse is full yet the blood is scant, this is called 'otherwise.' When the pulse is scant yet the blood is abundant, this is called 'otherwise.'
When the qi is abundant yet the body is cold, this is contracted from cold damage. When the qi is deficient yet the body is hot, this is contracted from summerheat damage. When food intake is abundant yet the qi is scant, this is contracted when there has been some loss of blood, or when dampness settles below. When food intake is scant yet the qi is abundant, this is because evil qi lies in the stomach and also in the lung. When the pulse is small yet the blood is abundant, this is heat retained within drink. When the pulse is large yet the blood is scant, this is because wind qi is present in the vessel, and fluids and beverages cannot be taken in — this is what is meant.
Now, excess means that qi is entering; deficiency means that qi is departing. When the qi is in excess, there is heat; when the qi is deficient, there is cold. When inserting the needle for a condition of excess, the left hand should keep the needle hole open. When inserting the needle for a condition of deficiency, the left hand should close the needle hole.