While I've never thought about this in terms of physical or spiritual, I've always kind of thought of this concept of yin and yang when I read 2 Nephi 2:11: "For it must needs be that there is an opposition in all things. If not so ... righteousness could not be brought to pass, neither wickedness (etc.) ... Wherefore, all things must needs be a compound in one..." And then I have that cross-referenced to Alma 42:16, "Now, repentance could not come unto men except there were a punishment, which also was eternal as the life of the soul should be, affixed opposite to the plan of happiness, which was as eternal also as the life of the soul." This concept of opposites really being a compound in one and punishment being affixed eternally opposite to the plan of happiness has always resonated with me, and again, I kind of think of it when I think of yin/yang. Worldly/cultural understanding of an eternal concept. Sorry if this isn't clear - too many things going on here demanding my attention!