Zhīmǔ from Běncǎo Jīngjiě 《本草經解》 (c. 1724 CE), attributed to Yè Tānshì 葉天士
氣寒，味苦，無毒。主消渴熱中，除邪氣，肢體浮腫，下水，補不足，益氣。
Its qì is cold, flavour is bitter, not poisonous. It governs dispersion-thirst with heat in the interior, eliminates evil qì, puffy swelling of the body and limbs, watery diarrhoea, tonifies insufficiency, increases qì.
知母氣寒，稟天冬寒之水氣，入足少陰腎經；味苦無毒，得地南方之火味，入手少陰心經。氣味俱降，陰也。
Zhīmǔ’s qì is cold, it is endowed with water qì of heavenly winter-cold, it enters the foot shàoyīn kidney channel. Its flavour is bitter and is not poisonous, it is virtued with the fire flavour of the southern direction, it enters the shàoyīn heart channel. The qì and flavour both descends, it is yīn.
腎屬水，心屬火，水不制火，火爍津液，則病消渴；火熏五內，則病熱中。其苦之者，苦清心火，寒滋腎水也。
The kidneys belong to water, the heart belongs to fire, when water cannot restrain fire, if fire scorches the jīn-fluids and yè-humours, then the disease of dispersion-thirst occur; if fire fumes the five internal [zàng-viscera], then the disease of heat in the interior will occur. [Because] it is bitter [flavour], and bitter clears heart fire, and cold enriches the kidney-water.
除邪氣者，苦寒之味，能除燥火之邪氣也。
Regarding eliminating evil qì, its flavour is bitter-cold, so it is able to eliminate the dry and fire evil qì.
熱勝則浮，火勝則腫；苦能清火，寒能退熱，故主肢體浮腫也。腎者水藏，其性惡燥，燥則開合不利，而水反蓄矣；知母寒滑，滑利關門而水自下也。補不足者，苦寒補寒水之不足也。益氣者，苦寒益五臟之陰氣也。
When heat is prevalent there will be floating, when fire is prevalent there will be swelling; bitter [flavour] is able to clear fire, cold [qì] is able to abate heat, therefore it governs puffy swelling in the limbs and body. The kidneys are the water zàng-viscus, their nature is to be averse to dryness. When there is dryness then opening and closing [of the bowels] is inhibited, and water will on the contrary accumulate; Zhīmǔ is cold and lubricating, it can lubricate and disinhibit the opening and closing [of the bowels] and then the water will naturally descend. Regarding tonifying insufficiency, the bitter-cold tonifies the insufficiency of cold-water. Regarding increasing qì, the bitter-cold increase the yīn qì of the five zàng-viscera.