I thought about this two days ago on 9/11, about how every person who suffered a loss was grieving over one tiny person out of billions, but that each of those people takes up the space of the universe. I read somewhere that the Talmud says "he who destroys one life, it is as if he had destroyed the entire world" which articulates what I'm not sure I'm able to express clearly here.
In physics there is a phenomenon known as Caesar's last breath which essentially states that we are all breathing molecules that were exhaled by Caesar, or any other number of ancient people. On September 11th, 2001, when smoke from the twin towers filtered over my Brooklyn apartment, a horrible kind of physics was changing the world irrevocably.
I suppose in some ways then we really are all connected in a base physical way. But I fight against the notion that we are all "one." Like most people these days I take yoga, and while it's good for my body, part of my mind still rebels against some of its tenets. I do believe in seeking acceptance, and will still work on meditating and reading self-help books and practicing presence. But I have to wonder if those who lost someone on 9/11, particularly a son or daughter, can truly accept. I don't know--I was lucky enough not to lose anyone that day, and I hope against hope that I will never have to know.