All of us face barriers--physical, financial, temporal--every day. Some are unquestionably real. But others are plainly artificial--expectations about how well a given system can function, or how much change is too much, or what kinds of behaviors are acceptable. The next time you encounter such a barrier, imposed by people who lack your imagination and drive and creativity, think hard about ignoring it. Solving a problem is hard enough; it gets that much harder if you've decided beforehand it can't be done.