Only you, not only me

some "old folks" said to younger folks (http://www.overcomingbias.com/2011/09/aged-wisdom.html):

"You might look inside yourself and think you know yourself, but over many decades you can change in ways you won't see ahead of time. Don't assume you know who you will become. This applies all the more to folks around you. You may know who they are now, but not who they will become."

I also have found this to be true, even in my relatively short lifespan.