Si Junzi Tang has four ingredients: ginseng, licorice, atractylodes (baizhu), and hoelen (fuling); it is derived from Lizhong Wan (Pill for Warming the Center) of the Shanghan Lun
by replacing the warming, spicy ginger with the bland, neutral hoelen.
As a result of this single herb change, the earlier chill-dispelling
prescription is altered to form a more moderate spleen-tonifying and
moisture-resolving formula.By calling the formula “four gentlemen,” one of
the implications is that the four ingredients all have an equal status
in the formula. By comparison, many formulas are described as having a
ruler (emperor), minister, assistant, and aid (see: Designing a personalized Chinese herb formula).
Despite the formula’s name, some authors differentiate roles for each
of its ingredients and specify that the four work harmoniously together
(but are not equals). This explanation is not as satisfactory, since
the characteristic of harmonious action among ingredients is attributed
to many prescriptions that are named in the ordinary manner. Thus, for
example, in the book Formulas and Strategies (1), which attempts to provide roles for individual ingredients of the formulas it describes, ginseng (or codonopsis, dangshen,
used as a substitute) is said to be the ruler; atractylodes is the
minister; hoelen is the assistant; and licorice is the envoy, yet each
of the herbs has essentially the same function. Licorice is as much a
key herb in the prescription as ginseng, though in many other formulas
it is mainly used to moderate the strong flavor of a decoction or
harmonize the action of ingredients with diverse properties.