There is no middle line in nature. The Creator merely prepared all the conditions for the creature to create a soul on its own by building the middle line using a system of two lines. Therefore, the middle line, which we construct out of two lines, is something completely new.
The gradations of dark and light, and good and evil come to us through sensations of these two lines. However, spirituality is neither the right nor the left line. Spirituality is the middle line, the organ of perception (Kli), which we build from two lines and the Light that fills it. It is an entity that did not previously exist. We succeed in creating it out of two forces.