WHAT'S THE MOST ASTONISHING THING YOU'VE SEEN OVER YOUR LIFETIME?

It's been a long way from the wheel to here

I have to say that I visited a thought that I carry around with me every single day.  It is a thought that is almost as old as I am.  The thought itself is simple enough, but the ideas that it engenders are sometimes challenging and daring.  They are sometimes like ear worms.  They just won't go away and I either have to live in the hope that they will go away of their own volition or learn to live with them.  Most of them come and go and only arouse me when I least expect it.  So many of them catch me unawares.  Like when I am driving or otherwise incapacitated by the lack of tools, time or space to record the episode.  Today was one of those days when the thought that I live with is that human beings are inveterate creators invaded my mind.  Human beings seemingly have an infinite ability to discover new ways to make old things better or to make completely new ones out of preceding realities.  Today, for instance I had some questions come to me that I have had a number of times before during my short life.  For instance, "How many really new, never before existed things are invented or introduced into our lives over the course of, let's say, 75 years?"  Or this, "What is the original musical instrument?"  I then had this idea again today, "Who decided how to pronounce human language?"  Who found out that cranberries are good to eat?"  "How many people died from trying to eat stuff that is poisonous?"  And I consider these easy, compared to cell phones and such.
Through it all, I remembered an assistant of mine in Tijuana who was fond of asking me my opinion about stuff because he thought that at my "old age" I might have acquired some "wisdom" along the path of life.  I was only 57 or so.  But anyway, he asked me the question about what I considered the most astonishing thing I had experienced or observed.  I told him then and I tell you now, it is the discovery of how to transplant human organs from one being to another.  All the other stuff is nothing.  Transplants are life.  So I like them best.  
However, they too cause some maddeningly tortuous challenges to those who want them, those who need them and to those who have the organ in their "possession."  I have no answers, just the questions, the challenge and awe as I stand aside and watch it all happen.