I thought about this a great deal when I was about 17 years old. Being in a household filled with women, we had a multitude of fashion magazines around. Being a bright kid, I started pondering why fashions became fashions, the fads and the trends. I wasn't thinking about what was the appeal of particuliar items but more the mechanism that worked in the form of mass appeal. Something had to be operating there, gearing us to find certain things attractive and others, not.
I realized that everything has its source, a beginning point. One person does something and it stimulates a positive reaction and emulation. Then, I realized that this isn't just limited to fashion but entire ways of thinking could begin this way as well. Even a catch phrase can spread like wildfire. It showed that we are all intrinsically connected like points on a spider's web. A vibration at one point can and will stimulate the entire web. It can be as minute as one person cutting off another person on the road. This person can become irritable and pass that irritability onto the next person they meet, who then passes it along as well.
It can be as minor as emotions or as visible as fashions or as momentous as in entire ways of thinking. The stronger the impulse, the stronger and wider the response. 9/11 stimulated all sorts of new trends everywhere. Greater spirituality, less eclectic styles, and even home interiors started to turn towards a more "zen" feeling. We are in the midst of a spiritual trend now and perhaps that is one some of you are feeling. It's just the motion of the great web of human life responding to 9/11 and gaining momentum by current events.