Lately, I've been thinking about two different psychological processes. One is the process of identification with others. For example, children identify with their parents. As young adults, we often identify with someone we admire, or even worship. But although the admiration is conscious, the identification is less so. Thus, we may find ourselves adopting ideas and attitudes of this people even when those ideas and attitudes have nothing to do with the reason we originally admired them. It is as though we unconsciously imagine that if we become like them, we will also acquire the wisdom or beauty they have. And once the psyche really does believe that these attitudes are its own, it is virtually impossible to un-do the process, even when it becomes clear that those ideas or attitudes don't serve us.
The second kind of unity is when we realize that we in fact are one with someone (or everyone) already, that it is our basic nature. In this kind of unity, the self doesn't take in something from the outside; rather, it sees itself in a new, expanded way. Oh, I'm so much larger than I ever imagined! It's as though the self, instead of taking attitudes or characteristics in from the outside to make itself bigger, realizes that it already is infinitely large and doesn't need any additions.
And, I suppose that the motive for the former process could be said to be the desire for the latter. That is, we want to be larger than we experience ourselves, and if the only way we can imagine to do that is to identify with others, then that is the way we will do it. But it never satisfies; only the second kind of unity satisfies.