A lesson many scientists should learn:

Of course, the trick isn’t to "know it all," but to know what you don’t know. Or to be able to figure out what you don’t know, which is difficult, because you don’t know it all.

Since coming to graduate school, I've observed many condescending exchanges between people who often don't know the limits of their own knowledge. I think this "personality quirk" is more common amongst those who are good speakers—after all, it's easy to convince yourself that you're the smartest one in the room when those around you don't sound as eloquent as you do. So this got me to thinking, "how indicative is verbal communication skill of natural intelligence?"

I, for one, have a tendency to overvalue rhetoric proportional to its utility. I stumbled across this blog's archive that reminded me that it is too easy to confuse good speaking ability with intelligence:

I have often attributed, I think, too much value to eloquence. Somewhere along in my education, I mistakenly equated the ability to write and communicate fluently with the ability to think rationally. While they are not entirely separate, the one does not necessarily imply the other... Intelligence is not necessarily a prerequisite to eloquence, nor is eloquence necessarily an indicator of intelligence.

It's unfortunate that there are a great many students at top-tier graduate schools who have problems separating intelligence from good oral rhetoric. I think the ability to separate these two is of the greatest importance particularly for scientists, because we should always require good evidence and not be overwhelmed by masterful speaking.