Traditional Chinese medicine believes that yin is a very important substance, which includes blood, body fluids, and semen. In traditional Chinese medicine theory, yin and yang are interdependent and mutually restrictive. Therefore, when yin is insufficient, it can lead to various symptoms in the body. In traditional Chinese medicine treatment, saving yin is a very important treatment method.
Saving yin does not lie in blood, but in fluids and sweat. The meaning of this sentence is that the method of saving yin is not achieved through supplementing blood, but through supplementing body fluids and sweat. This is because in traditional Chinese medicine theory, blood and body fluid are different substances. Blood is a liquid, while body fluid is a special substance in the liquid that exists in various parts of the body, including the skin, muscles, organs, etc. Sweat is also a type of fluid in the body, which is converted from body fluids.
中医认为，阴是一种非常重要的物质，它包括血液、津液和精液等。在中医理论中，阴与阳是相互依存、相互制约的，因此，当阴不足时，就会导致身体出现各种症状。在中医治疗中，救阴是非常重要的一种治疗方法。

救阴不在于血，而在于津与汗。这句话的意思是，救阴的方法并不是通过补血来达到的，而是通过补充津液和汗液来达到的。这是因为，在中医理论中，血液和津液是不同的物质，血液是液体，而津液是液体中的一种特殊物质，它存在于身体的各个部位，包括皮肤、肌肉、器官等。而汗液也是身体的一种液体，它是由津液转化而来的。