In the previous chapter, we discussed the skill of getting to know the student's inner and outer realities. This skill corresponds to the sefirah of da'at ("knowledge") because every state of awareness or recognition is an expression of da'at.
Da'at lies on the trunk of the Tree of Life of the sefirot, and so combines aspects of the right branch (love and expansion) and the left branch (strength and restraint).
Knowledge of essence and soul derives from the right, expansive side of da'at which enables a person to penetrate into the deep unrealized potentialities of another. It requires a connecting of souls which is always a state of chesed ("loving-kindness"), a state associated with expansion. Knowledge of outer realities, environment, surroundings derives from the left side of da'at, the state of gevurah ("strength"), which is associated with restraint. This type of knowledge requires the educator to make the effort and take the time to get to know his students, an effort which often requires self-sacrifice. The restraint element of gevurah enables the expression of love from a distance, overcoming barriers of time, or space, or tiredness. It is much easier to express love when in a state of closeness (the chesed side of da'at), whereas the ability to overcome distance demands a different kind of effort (which draws upon the gevurah side of da'at).
But by far the dominant influence of the sefirah of da'at is as a force of unification.
Each of the properties of the soul has a different Name of God corresponding to it. For example, Elohim is the Name of God relating to might, judgment, courage, and fear. And El is the name of God which relates to loving-kindness. The sefirah of da'at unifies these two polarities. All the Names of God associated with da'at are variations on the unique four-letter Name of God, the Tetragramaton, which indicates the most essential nature of Divinity, and in particular implies the attribute of mercy. In the heart, chesed and gevurah are separate emotional forces, each relating to a different Name of God. But true essence, by definition, must necessarily transcend this duality. At the level of da'at, these two poles are unified and as such, they resonate with the Tetragrammaton which embodies the secret of unifying all reality.
In the case of teacher and student, this comes into being as the teacher converts his sense of distance from his student into a sense of deep recognition and appreciation that reflects the union of souls.