“The theory of Mussar that predominates in this commentary begins with an analysis of human consciousness, which is described as unfolding along an arc between the yetzer ha-ra and the yetzer ha-tov. These traditional terms, usually translated as “the evil inclination’ and “the good inclination,” delimit the field within which all human activities take place. However, in order to engage in a deeper exploration of wha Jewish traction might mean by these terms, we must define them differently. I would suggest that the yetzer Habra cannot be understood simple as evil in the conventional sense, based on the Rabbis’ assertion that “human beings were created with both the yetzer ha-ra and a yetzer ha-tov, and were it not for Torah the tater ha-ra would triumph over the yetzer ha-tov in all cases. Since the yetzer ha-ra is essential for normative human activities, i.e., those activities necessary to assure our survival in the world, we understand it to mean the material urge that complels us to survive in the world and to bend the forces of material nature to our will; it is the inclination to work for the self. Conversely, the yetzer ha-tov represents the equally innate inclination to please or to serve another. Thus, in every instance human beings are presented with a choice between the self (yetzer ha-ra) and the other (yetzer ha-tov).
Because the vicissitudes of everyday life can be so overwhelmingly difficult the meter ha-ra must be exercised with ever greater power and, like a muscle, its strength soon grows out of proportion to the strength of the tether ha-tov. With Mussar practice, however, we can reengage our yetzer ha-tov, our desire to sere another before ourselves, without denying the legitimacy of the yetzer ha-ra. The complex and incremental program of self-scrutiny and self-correction by which we can accomplish this is described in A Responsible Life, but is also reflected and referenced in Mesillat Yesharim. It consists of a daily heshbon, or accounting of the soul, that is conducted by reflecting on specific character traits, or midst, like order, patience, equanimity, and humility. This allows us to focus on specific interactions with other people and to evaluate our behavior in regard to them.
Mesillat Yesharim by Moses Hayyim Luzzatto