Three categories of medicinals of The Divine Farmer’s Roots and Grasses Classic (神农本草经 shén nóng běn cǎo jīng). Top-grade medicals are those that are nontoxic and can be taken for long periods without harming the body. Medium-grade medicinals are those that are nontoxic or not greatly toxic and can treat disease and supplement vacuity. Low grade medicinals are ones that are toxic or harsh in their effects, cannot be taken over long periodsand are used to dispel heat and cold evil qì or to break accumulations and gatherings. The classification system of The Divine Farmer’s Roots and Grasses Classic (神农本草经 shén nóng běn cǎo jīng) is now considered to lack precision and consistency, some medicinals marked as top grade, for example, being toxic.