What do I know for sure?

What do I know for sure?  I came across this question while reading O magazine at the gym.  The article was about people who had wise answers to this question.  I never made it to their comments.  I was so riveted by this question, that I continued to ponder it for awhile.  So...what do I know for sure?  Fortunately, not much.  I am grateful this insight, although, I still at times catch myself pursuing avenues of thought that convince me that I do know something, especially what I think is absolutely right for someone or something.  Of course, being the oldest sibling has definitely groomed me for this automatic, habitual thought process.  Doesn't being the oldest mean you know what is best?  Luckily some of my greatest humbling lessons have come from my siblings.  I have learned, painfully at times, that I do not know what is best, and when I hold on to thinking that I do know what is best for others, I really miss out on learning and understanding something about them.  What do I know for sure?  I am sure I really, truly, honestly know nothing.  So paradoxical, to be sure about nothing.   Yet, it is here in this place of openness and curiosity that I truly experience the wholeness and perfection of life and people.  My hope is to always remember I do not know.  Please show me.