I hear a little knowledge is a dangerous thing. Today in a meeting with a principal I piped up with a concept I had just been reading about- just STARTED reading about- and I seem to have talked myself into giving a two hour presentation about it. In two days.
I'm not sure that's exactly what the originator of the saying meant (the internet says it showed up first in Alexander Pope's writings), but that's what it means to me today.
An equally meaningful lesson would be "keep your trap shut," which this same principal has suggested to me (wisely, with respect and humor) time and again in advance of these types of meetings.