You are either asking, "Who the hell is Carl Jung, and what's the big deal on one sentence?" Or: "Who the hell do you think you are, buckeroo, to decide Jung's best thought?"
Let's get to the grandfather of spiritual psychology's sentence in question, which is this:
"Each is deceived by the sense of finality peculiar to the stage of development at which he stands."
Boom. Mic drop. (Neither of which Jung would ever say.)
But I will. Because on page 46 of Jung's Modern Man in Search of a Soul, that sentence came off the page at me like a right hook to the third eye. At the same time, it was also a healing salve.
The wording is a bit stuffy, but it works: Each person is under a delusion that they are done, they have completely -- or nearly completely -- figured out life. Or politics. Or religion.
Do you know people who are pretty naked about this? They are the gross examples -- the blowhards, the arrogant, the just-listen-to-me-and-you'll-have-a-clue goofballs.
In politics they are easy to spot: commentators whose favorite word is "moron", and whose favorite sport is condescension.
In religion they are a little subtler: clergy and lay writers of all stripes, who feign compassion for the great unwashed who "just aren't there yet." When religious people are unsubtle, you will just be declared Hell-bound and dismissed.
You and me, we're not them. Yet, sadly, we don't get to project this condition off of ourselves so easily. The enemy of realization, of understanding, is not ignorance. It is not lack of learning. The enemy of understanding is certainty.
It is easier to see this certainty in ourselves when we look in our past. For instance, I would like here and now to apologize to anyone I ever talked to when I was 19 years old. Although I didn't go around saying it, I was quite insightful, if you please. And if I could just tell you what is True about the world, you'd be much happier, let me tell you.
It reminds me of a line from an old Seal song, Don't Cry, about younger days:
"...we were older then, and we lived a life without any doubt."
The challenge for many of us is to grow out of that certainty. Out of our assumption that knowing about stuff -- how the world works, God, global politics, love -- is of any real value.
The illusion is that certainty is a sign of smartness. Really, the opposite is true.
At a men's spirituality group I attended for a few months, there was a bright guy who was easy-going and humble about his own thoughts and ideas. But when he would launch into concepts he learned reading philosopher Ken Wilbur, he would drop into this certainty zone, into this mode of instructing us in What Is True -- almost scolding us. (I never heard too much, because I stopped listening when he got that way.)
Deceived by a sense of finality. If the ways of the world and the things of the spirit look the same to me as they did 20 years ago, I am trapped in certainty.
And no, it's not that everything is fluid and unknowable and relative, either. But what I realized is that it is, literally, impossible to learn anything about a subject when you are certain about it. The internal "sense of finality" is a sign of presumption of complete understanding.
Me, I'd rather listen to you tell me your tentative, half-baked, incomplete notion of how romantic relationships work. Or explore with you different ideas of the nature of God, without either of us trying to "win" a Truth battle. I'd rather hear from someone who is willing to look foolish, and risk saying an unexpressed thought.
And yes, maybe when you do that, you wind up metaphorically doing a face plant into the mud.
Then, though, then tell me what you see, when you raise your head and look up from the ground with the new eyes of experience.