One of my favorite concepts (if one is allowed to have favorites) is ein sof (or ein od, or ein od milvado).
A rosh yeshiva and mashpia once told me that when you say "echad" in the shema, you should envision the godliness in everything.
Yet at the end of the havdalah recitation, H' is blessed for making a separation between the sacred and the profane. In the language of math set theory, the universal set is divided into the sacred and, its compliment, the profane.
(I don't think the subsequent distinctions are of the same genre.)
I could understand how one could look at things as either or. But why is H' blessed for engendering that distinction.
Thanks