Since there are no words in the spiritual world to describe their spiritual feelings, Kabbalists call these experiences branches, a word taken from our world. Therefore the language used in books on Kabbalah is called the language of branches. It is a language that borrows words from our world and uses them to identify spiritual experiences. Since everything in the spiritual world has an equivalent in the physical world, each root of the spiritual world has a name and the name of its branch. And because we cannot describe our feelings precisely and do not know how to measure or compare them, we use all kinds of auxiliary words to help.
Courtesy of http://www.youtube.com/watch?v=hMM3LpCkZQE