I said, "Well, why do you believe in the Klein Bottle?" He said, "Because I can imagine it." I said, "You don't have to imagine a Mobius strip. It's right there in front of you!" But [Buckminster Fuller] couldn't see how that could involve a cross cap, meaning something that couldn't be reduced to a two-dimensional surface. Which it does. It's because he was thinking that the matrix was the thing that a fly could walk over the edge of, like a torus.