A few weeks ago, my colleague and I were chatting and she was talking about the fact that there are some things are brought to her attention or meetings she's invited to where she knows little or nothing about the subject matter.
I smiled and said that's fine because I "thrive" in not knowing it all. Now that's not to say that I don't know anything...I know some things but I don't know everything. I believe that not knowing it all gives one (me) room to grow.
On the other hand, while it's ok not to know everything I believe that it is very important to know what you do know well.
In professional & personal circles, people have more respect for those who "know-it-well" than those who carry around as if they know-it-all.
In the corporate world, there's quite a bit of talk about specializing in a body of knowledge to become a Subject Matter Expert (SME) or a Technical Authority (TA). Did you know that those acronyms also stand for "Small & Medium Enterprises" and "Turn-Around" respectively? Small & Medium Enterprises aspire to get bigger and Turn-Arounds are meant to improve the performance of the equipment - these are pointers to the fact that it's better to know-it-well and keep learning more, growing and getting better as against capping your willingness & ability to learn. Be a know-it-well not a know-it-all.