Originally Posted by

**Jacobsen** Thanks for those neat examples Piper and Oplag. I really like that quote from J.Lewin. It seems like one of the weird things with sets which contain themselves as members is that you can end up with something that looks like

A = {x1, x2, ..., A = {x1, x2, ..., A = {x1, x2, ..., A = {...} ..., xn}..., xn} ..., xn}

which would be a set that contains an infinite amount of sets even when A was thought to be finite. Is this a misguided interpretation or would that be one of the kind of objects we would look at in non-well founded set theory?