As an aside, one useful (but not quantifiable) definition of intelligence is the size of the intuitive leaps a person is able to make: how complicated things have to be before they're not "obvious" to you. This is part of what can make it hard to communicate with people of lesser intelligence. (Note that "intelligence" in this context is as much crystallized as fluid.)
For example, I may read a mathematical theorem, and where the author says, "Because [X], it is obvious that [Y]," I get totally confused and have to spend thirty minutes figuring out how they got from X to Y, and even when I get there it's kind of fuzzy in my head and I have trouble following the steps after Y. I'm just not following something that's obvious to the author, and if I told him so, he might look confused and throw out a glib explanation that would also baffle me. (Or, if he has experience teaching people at a lower level, he might have a good explanation worked out.) It's hard to relate to people who just can't see things that you see.
I remember an individual who, when she was 10 and I was 12, didn't realize that the Word of Wisdom's "hot drinks" included iced tea. I recall friends from high school who didn't think the prohibition on early dating applied to having boyfriends, only to going on formal dates with them. I still can't wrap my head around either of these conclusions--how can it not be obvious that they're wrong? How can an active Latter-day Saint not realize that coarse language is abhorrent? Our mathematician might be just as baffled that I can't follow his arguments. In fact, there are lines of reasoning which are obvious to me now which I distinctly remember being non-obvious to my younger self, which is one reason I believe that you can increase your intelligence with time and effort.
P.S. I should note that exactly who is the "lesser intelligence" in a situation may depend upon subject matter and context, too. Americans, generally speaking, are enthralled with the idea of a soul mate, someone who intuitively "gets" you. Someone to whom your thoughts and feelings are as obvious as they are to yourself. It should be apparent why this is a high bar to clear. :)
"The presentation or 'gift' of the Holy Ghost simply confers upon a man the right to receive at any time, when he is worthy of it and desires it, the power and light of truth of the Holy Ghost, although he may often be left to his own spirit and judgment." --Joseph F. Smith (manual, p. 69)
Be pretty if you are,
Be witty if you can,
But be cheerful if it kills you.