All of the family photo albums my parents made when my brother and I were little kids include classic shots of me in tears.  I guess it is pretty funny in retrospect, but it sure didn't seem so at the time.  Now seeing my daughter in tears makes me wonder about the frustration kids must feel so often growing up.  Trying new things -- failing -- sometimes succeeding -- it must be stressful.  Since I've been a mom, it seems clear to me that this frustration is why we don't remember being babies.  Learning to eat and walk, growing teeth, climbing stairs and furniture and falling on our butts or our heads -- the stakes are too high for it to not be monumentally frustrating.  So once we learn it, we forget it -- or the process of it, anyway.  

Some people say they don't remember the pain of childbirth.  Maybe this is a similar thing -- it is so meaningful that we don't want it to live in our memories negatively -- we want it to be filled with the tearful kisses and joy of holding that new life for the first time.