I think some of our greatest spiritual teachers, throughout history, have given us some clues.
In this regard, I especially appreciate the Shema of the Jews, which seems to me to speak to an underlying unity/union of all Creation:
“Hear, O Israel: the LORD our God, the LORD is one.”
People seem to think it simply means that there is only one God, as opposed to a multitude of gods. I think there’s a lot more to it than that.