Remove all the space within the atoms making up the human body and every person that's ever lived would fit inside a baseball. ~Brian Greene
Adam Rifkin stashed this in Quotes!
Theoretical physicist Brian Greene – author of The Elegant Universe and co-founder of the World Science Festival – takes a moment out of his undoubtedly busy schedule to remind us how little we amount to once you subtract the space between some of our ittiest bits and pieces.
Are we going down to hadrons and leptons here or getting into quarks?
Brian Greene was not clear -- probably quarks, but really it's just hyperbole for illustration.
An io9 commenter says they could have taken it even further: "The entire mass of the earth has a Schwarzschild radius of 9 mm. So, really, the entire biomass of all of humanity could fit into something smaller than a grain of sand."