In the “Preface to the Book of Zohar,” Baal HaSulam explains that the science of Kabbalah examines everything with regard to the soul. This is because we are not actually aware of anything outside of ourselves; rather, we reveal, perceive, and evaluate things through our feelings.
Therefore, when we read about the processes that occur between Zeir Anpin, Bina, and Malchut, and the connection and actions between them, it is all happening inside us, in the connection between others and me. We learn about what happens in our soul, or what our soul feels and reveals to us. Where it feels and reveals is only inside it.
That connection between me and others is, in fact, my soul. However, right now we feel that we exist in our inner corporeal body; this is our world because we don’t perceive anything else.