Each medicinal substance is characterized along four properties (si qi: cold, hot, warm, cool) and five flavors (wu wei: sour, bitter, sweet, pungent, salty), and these sensory-thermal qualities, not the substance's physical origin, determine its therapeutic action. A remedy is matched to an illness by opposing qualities: cooling agents for heat conditions, warming agents for cold ones.
Substances are grouped by natural kind (herbs, trees, insects, metals, stones, waters, fowl, beasts) rather than by the disease they treat, so a single catalog entry records a thing's identity first and its uses second. This arranges knowledge around what something is, letting one substance carry many unrelated applications under a single heading.
For each entry the text compiles and names prior authorities, then flags inherited errors by correcting misidentifications, exposing fabricated remedies, and separating substances that earlier texts had conflated. Accumulated tradition is treated as data to be audited rather than accepted, with the compiler's corrections recorded alongside the sources they overturn.