four good roots ［四善根・四善根位］ ( shi-zengon or shi-zengon-i): Also, four roots of goodness, four roots of good, or the stages of the four good roots. Stages of practice taught in Hinayana Buddhism. The preparatory practices leading to the way of insight, the first of the three ways. The way of insight is the stage at which one gains insight into the four noble truths. It is followed by the way of practice and the way of the arhat, or having no more to learn. One who has attained the four good roots enters the way of insight. Root here means the source of an attribute or virtue. Because these four form the foundation or source of the capacity to enter the way of insight, they are called roots. The four good roots, along with the three stages of worthiness, constitute the seven expedient means. Both the four good roots and the three stages of worthiness refer to the stage of ordinary people, and the way of insight and the subsequent stages, to the stage of sages. The stage of ordinary people is divided into two: the inner rank and the outer rank. The former, or the higher rank of ordinary practitioners, corresponds to the four good roots, and the latter, or the lower rank of ordinary practitioners, corresponds to the three stages of worthiness.
The four good roots are (1) the heat stage, or the stage in which one approaches wisdom without outflows, or earthly desires, and obtains the type of good roots still tainted by outflows, just as one approaches a fire and obtains heat from it; (2) the peak stage, or the stage in which one’s good roots are still unsettled but one obtains the highest of the unsettled good roots; though the peak stage is the stage of possible regression, even if persons in this stage recede from it and fall into hell, the good roots represented by the peak stage cannot be wiped out; (3) the perception stage, or the stage in which one understands the doctrine of the four noble truths, and one’s good roots are settled; one who has entered this stage will never fall into the evil paths of existence; and (4) the foremost worldly stage, or the stage in which one obtains the highest of the four good roots, though these good roots are still tainted by outflows. One who has reached this stage in time will enter the way of insight and become a sage. The concept of the four good roots was later applied to the stages of Mahayana practice with some modification.