Justice Anthony Kennedy nailed it when he said the Supreme Court was in uncharted waters when considering same-sex marriage. He might also have said that this means that society is unburdened with myth and legacy on this issue and can consider it almost on it merits; whereas homosexuality is as old and permanent as time, marriage between homosexuals is a new concept in the organization of human affairs.
Actually, the justices are facing something antithetical to their purposes: a clean slate. For the rest of society, a clean slate is almost unachievable. But when it does happen — when law, conduct and invention are unhampered by the legacy of the past and myths that are codified into principles — wonderful things happen. For example:
1. The U.S. Constitution, where the old building blocks of political organization were rearranged into something totally new and marvelous.
2. The computer age, where ideas and inventions — largely because they weren't limited by previous ones — have changed the entire human system of work and communication.
3. Modern art, where millennia of tradition had established rigidities that defined what was art and its production, added to the sum of the medium and allowed a new voice of expression.
4. Rock and Roll, where a new form eclipsed the popular music of the time and was able to borrow from the blues, jazz and other sources without accepting their rigidities. It vastly enlarged the musical firmament.