Who am I?

I remeber reading this poem in , may be, class 1 , "I am in the Pistol, not in the gun, double in the moon but not in the sun. Who am I?"

Pretty simple to answer , isn't it? of course, it's the letter O....

But, seriously this question is not that starightforward to answer.. at least not for me....

So who am I? Whenevr I spend a few moments to think about myself, moments cross over into into longer moments .. then even longer moments ... still the question virtually remains ...not fully answered ... to my horror... it dawns onto me .... how little do I know about myself !!!!