Well, I guess you're not going to work from my hint 
Trying to define a "set of all sets" leads to a paradox, since it must contain its own power set, whose cardinality is strictly greater than its own. So to avoid being able to define such paradoxical sets in set theory, you need this: http://en.wikipedia.org/wiki/Zermelo%E2%80%93Fraenkel_set_theory#3._Axiom_schema_of_specification_.28also_called_the_axiom_schema_of_separation_or_of_restricted_comprehension.29
Notice from the link what the "ask Russell" hint meant now?
Yeah i've read the before..... but i didn't understand it until we had this whole 1 divided by zero conversation... that just blew my mind So your claiming that 1/0 dosen't = undefined
No, I was saying exactly that 1/0 = undefined. I was being cute.Trying to define a "set of all sets" leads to a paradox, since it must contain its own power set, whose cardinality is strictly greater than its own. So to avoid being able to define such paradoxical sets in set theory, you need this: http://en.wikipedia.org/wiki/Zermelo%E2%80%93Fraenkel_set_theory#3._Axiom_schema_of_specification_.28also_called_the_axiom_schema_of_separation_or_of_restricted_comprehension.29
Notice from the link what the "ask Russell" hint meant now?
