Now the ten kinds of fruit [that represent the World] of Creation have been purified of everything that relates to the forces of evil (pesolet)41Literally, “of all refuse.” and are left completely good. But a barren tree [represents] the opposite. It corresponds to pure evil, containing nothing but the kelippah. Just as the ten kinds of fruit [that correspond to the World] of Formation have an edible exterior and a hard interior, the kernel within, so it is with the kelippah.42It bears no edible fruit. Thus it contains no divine sparks. When a fallen holy spark is great, the kelippah is not able to contain all of that light within itself. So [the kelippah] enters within the holiness and the holiness surrounds it.
The Fruit of the Beautiful Tree and the Forces of Darkness
Peri Etz Hadar 1:14