What's taken v. what's left.
A pint of blood from a guy with 7 pints is a bit different than 600 pints of blood from a guy with 6,000,000.
Especially considering that one could take 5,999,994 pints from the second guy and he'd still be no worse off than the first. So it's looking as if there is a helluva lot more excess than folks realize.
Arf