The G-dly Self
The "second soul" described in Tanya is the impulse for losing oneself in the Oneness of G-d. This chapter describes the selflessness of the "nefesh elokis" (G-dly soul) as opposed to the self-preservation of the "nefesh habehamis" (animal soul.) This soul is equally present within every Jew regardless of their spiritual standing. This is one's true self which one reveals by being connected to a tzadik.